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LABORATORY NOTES 



IN 



HOUSEHOLD CHEMISTRY 



FOR THE USE OF 



Students in Domestic Science 



BY 



H. T. VULTE, Ph. D., F. C. S., 

Adjunct Professor of Domestic Science in Teachers College, 
Columbia University, 



AND 

G. A. GOODELL, A.B., A.M., 

Instructor in Chemistry, Wellesley College. 



Easton, Pa. : 

The Chemical Publishing Company, 

1904, 



I OCT 28 1904 



' eoPY 3 



J 



\-' 



PREFACE. 

The following pages are written as a guide and intro- 
duction to the study of household science. It is not the 
object of the authors to put forth a work on the analysis 
of food and other kindred subjects met with in the 
practice of domestic science ; their sole aim is to throw 
some light upon the composition of food and other 
materials to the end that those practicing this most use- 
ful of arts may achieve better results by understanding 
the more important properties of materials with which 
they deal. 

Some knowledge of chemistry, both general and 
organic, is necessary and a clear idea of the essentials 
of physics is indispensable. 

It is hoped that teachers using the manual will com- 
municate with the authors in regard to any suggestions 
or improvements. 

The book is a pioneer in the subject and may be 
criticized on account of the selection of subjects; they are, 
however, those which have in the course of three years 
proved most useful to the authors' classes. 

The common and metric systems of weights and 
measures are used in the manual; in all exact experi- 
ments the metric system has been given the preference, 
but in cases where the experiment has a direct bearing 
on domestic science the common household units have 
been brought into play. 



CONSTRUCTION OF THE BUNSEN BURNER. 

Unscrew the tube, examine and light the inner jet. 
Examine the outer tube and collar that controls the air- 
ports. Turn off the gas and replace the tube. Now 
turn on the gas again, strike a match and approach it to 
the top of the tube. Always observe this latter pre- 
caution when lighting the Bunsen burner. Observe the 
character and color of the flame, move the collar on the 
tube and note the effect. Hold a piece of glass tubing 
near the top of the flame, remove from the flame and 
bend. Hold it in the same position in the yellow flame, 
and after removal observe the condition of the tube and 
try to bend it. Is there any apparent difference in the 
intensity of the heat developed ? lyOwer a piece of fine 
iron wire gauze half way in the flame, why does the 
flame fail to penetrate the gauze ? Apply a light above 
the gauze, explain the phenomena. Place a piece of 
paper on the gauze, lower it half way in the flame, notice 
the charred ring. Hold a splinter at the same point in 
the flame, note where it is charred and explain. Intro- 
duce the large end of a dropping tube into the flame near 
the tube, and approach a light near the exit. From the 
results of the last three experiments what is your idea of 
the combustion zone ? 

Carefully turn the gas down at the key, watch the 
effect, why does the flame disappear ? Now immediately 
turn the gas on full force and note the result. Approach 
a light to the upper end of the tube, observe the 
character of the flame, compare with the original flam^ 



MANIPULATING GI.ASS TUBING. 5 

as to color and heating effect. Strike the rubber tube a 
quick blow with the closed hand and explain the result- 
ing phenomenon. 

Make a simple drawing illustrating the structure of 
the Bunsen burner, with the gas and air supply and the 
zones of combustion of the flame. 

INSTRUCTION FOR HANIPULATING GLASS TUBING 
AND CONSTRUCTING SIHRLE APPARATUS. 

Two kinds of glass, " hard " and " soft," are used in 
making apparatus for the laboratory. Hard glass is very 
brittle and quite infusible in the ordinary Bunsen flame. 
It is used in heavy apparatus where a high temperature 
is required for heating dry, but never liquid, substances, 
as the latter would cause it to break. It can usually be 
recognized by the striations on its surface and by its 
greenish-yellow color, best seen at the end of a broken 
tube. 

Soft glass is less brittle than the other variety, is 
easily fusible in the Bunsen flame and is used in the con- 
struction of thin apparatus (such as beakers, test-tubes, 
etc.) for heating liquid, but never dry, substances. 

The tubing used by the student for bending, blowing 
and fitting up apparatus should be of soft glass. 

Cutting the Tube. — Glass tube up to one-fourth inch 
in diameter may readily be cut by making a slight 
scratch with a triangular file at the point of fracture, the 
tube is now grasped firmly in both hands holding the 
scratch outward and the thumb nails pressed against the 



6 HOUSEHOLD CHEMISTRY. 

inner side of the tube opposite the mark, give a slight 
bend outward, at the same time pulling apart; the tube 
will make a clean break and no injury will be received. 
Broken in this way the tube ends are sharp and should 
always be rounded by heating for a moment in the flame. 

Bending the Tube. — Take care that the tube is per- 
fectly clean and dry inside and outside before heating. 
Adjust the wing- top to the burner and after lighting, 
heat the tube lengthwise in the upper part of the flame. 
Revolve the tube so as to heat all parts equally; when 
soft, remove from the flame and quietly bend to the de- 
sired angle. In case no wing-top is available, the tube 
may be heated in the same way in an ordinary illumi- 
nating burner. The carbon deposited on the tube is 
readily removed, after cooling, by rubbing with filter- 
paper. 

Drawing the Tube. — Heat as before in wing-top or 
illuminating burner ; when soft, remove from the flame 
and quietly but steadily draw apart. On cooling, the 
tube may be cut with a file at any spot, and will furnish 
two pointed tubes. These are used for dropping tubes, 
by cutting to the desired length and rounding the ends 
in the flame. 

Closing the Tube and Blowing Small Bulbs. — Select 
a tube with thick walls, cut off a piece about a foot long, 
heat the square-cut end in the upper part of the ordinary 
Bunsen flame, revolving the tube continuously while 
heating; in a short time the tube will close. To blow a 



CONSTRUCTION AND USK OF TH:^ WASH-BOTTI.K. ^ 

bulb continue the heat for a few minutes longer, then re- 
move and blow quietly but strongly into the open end of 
the tube, continue the air pressure until the desired 
diameter has been reached, but on no account attempt to 
make a bulb of more than double the diameter of the 
original tube, as in this case the walls will be too thin. 
If it has been impossible to blow a bulb of the desired 
size in one operation, the tube may be reheated and blown 
again until the desired diameter has been reached. 

Glass rod may be cut, bent and rounded in manner 
similar to tubing. 

CONSTRUCTION AND USE OF THE WASH=BOTTLE. 

Select a clean eight-ounce wide-mouthed bottle, fit to it 
a rubber stopper pierced with two holes. Now cut two 
pieces of one-fourth-inch glass tubing, six and ten inches 
long, heat the longer piece in the wing-top flame about 
three inches from the end, when soft remove from the 
burner and bend to an angle of 45°. Heat and bend the 
shorter piece in the middle to an angle of 135°, round 
both ends of each tube in the flame, when cold moisten 
one end of the short tube with saliva and push it through 
one hole of the stopper, proceed in the same way with 
the longer tube but push it nearly up to the bend, so 
that when the stopper is inserted in the bottle the other 
end will just clear the bottom. Cut a piece of black 
rubber tubing two inches long, slip one end over the 
longer tube, make a jet by cutting off two inches of the 
pointed end of a dropping tube, round the rough end, 



8 HOUSEHOI.D CHEMISTRY. 

and when cool push it into the rubber tube. The bottle 
is complete and ready for filling with cold water. By 
blowing into the short tube, a fine jet of water will issue 
from the nozzle; by tipping the bottle upside down, a 
larger stream will issue from the shorter tube. 

Wash-bottles for hot liquids are made in the same way^ 
using a thin glass flask instead of a bottle. 

CARBON AND COriBUSTION. 

Wood contains moisture (H^O), resin (CxH^), starch 
and cellulose (CgH^oOj), oil (CxH^OJ, mineral matter or 
ash. 

Considerable heat is required to drive off the moisture 
and raise the starch, cellulose, etc., to such temperatures 
that they will decompose, yielding gases of a com- 
bustible nature; for example, CO, CH^, C2H^,C2H2, Hg; in 
this decomposition H^O is formed and must be driven off 
as a gas, much heat is also absorbed by the ash in form- 
ing new chemical compounds. In fact the fuel efficiency 
of wood depends entirely upon the relative volumes of 
combustible gas and charcoal furnished, and as the 
charcoal or carbon is the best solid fuel, the wood 
furnishing the largest proportion of carbon in this form 
is the best fuel, hence we find it advantageous to use 
hard wood. It must be understood that carbon or char- 
coal at a red heat combines with a limited amount of 
oxygen and forms a combustible gas, carbon monoxide, 
CO, a fuel of the highest heating efficiency. 

Coal is superior to wood as it contains less water and 



CARBON AND COMBUSTION. 9 

produces less by chemical change and yields the com- 
bustible gases and carbon (coke) in larger proportion. 
Hard coal is superior to soft, since it is a purer form of 
carbon and yields no combustible gas. Gas is superior 
to any solid fuel, as it has no water to vaporize and no 
ash. Gas containing CH„ C^H,, and C2H, is called 
illuminating gas and does not produce the heating effect 
of fuel gas composed of H, and CO. Even when both 
are used in the Bunsen burner, a glance will show that 
one will produce a large amount of H^O by combustion, 
while the other does not, and as water absorbs much 
heat, that producing the least amount will absorb the 
least heat. The reactions taking place will be given 
under the Bunsen and common burners. 

Destructive Distillation. — Make a capillary tube as 
directed, and insert it in a perforated cork. Now place 
in a hard glass test-tube small pieces of hard wood, in- 
sert the cork and clamp the tube and contents in a slightly 
inverted and inclined position on the ring-stand. 
Gently heat the tube in the flame, from mouth upward. 
From time to time try the exit tube with litmus paper, 
and then with the flame, continue the heating until the 
pieces of wood appear to be completely charred, but 
avoid burning the cork. Before allowing the tube to 
cool, carefully remove the cork, collect any liquid in the 
tube in a small dish, and close with a fresh cork. 
Observe the odor and general character of the liquid and 
test with litmus paper. When the tube is cool remove 
the charred material, carefully observe its character with 



lO HOUSKHOI.D CHKMISTRY. 

a magnifying glass, and make a rough sketch of its 
structure, float a small piece on water, and boil it for ten 
minutes, try another piece in the flame, burn another 
piece in a porcelain dish. Is there any residue ? If so, note 
its character. 

Repeat the same experiment using bituminous, and 
anthracite coal. Note any difference in the products of 
distillation of soft coal and wood. 

Arrange the results of these experiments in tabular 
form. 

Behavior of Mixtures of Gas and Air. — Fill a 250 cc. 
wide-mouthed bottle with about four-fifths air and one- 
fifth gas, collecting it over water, cover with a glass 
plate and shake thoroughly. Quickly replace the glass 
plate with wet filter-paper, pierce with a pencil point, 
apply the flame and note the result. Try the same ex- 
periment, using gas alone. 

Products of Combustion. — Hold a clean dry flask 
filled with cold water over a Bunsen flame and note the 
result. What compound is formed ? Explain. 

Substitute a pointed glass tube for the Bunsen burner, 
turn the gas low and light at the point, introduce the 
flame into a clean dry bottle and hold it there for a few 
moments, note the result and remove the tube. Again 
introduce it under the same conditions and note the 
result. Remove the tube, cover the bottle with a glass 
plate and turn off the gas. Pour about 10 cc. of lime- 
water into the bottle, shake well, note the result, explain 
and write the equation. 



ASH OF COAL OR WOOD. II 

The common burner can use gas of only the following 
composition, /. e., methane, CH^, ethylene, CgH^, acety- 
lene, C^H^, hydrogen, Hg, carbon monoxide, CO, and 
combustion proceeds according to the following equations : 

CH, + 20, ^ CO, + 2H2O heat, no light. 
2H, + O, ^H^O *' '' " 

2CO + O2 =2C0, " ♦* ** 

C^H, + O2 = 2H2O + C2 less heat, some light. 
2C3H, + O, =2H30 + 2C, " *' more '' 
The Bunsen burner mixes the gas with O, before com- 
bustion; this change afifects only the ethylene and acetyl- 
ene, as follows : 

C^H, + 3O2 = 2H2O -f 2CO, heat, no light. 
2C,H, + 50, = 2H,0+4CO, '' " '' 

ASH OF COAL OR WOOD. 

Wood Ash. — Burn a small piece of hard wood or char- 
coal on platinum foil until thoroughly ashed, cool and 
transfer to a small porcelain dish, add a small quantity 
(5 cc.) of distilled water, and heat to boiling. Is there 
any residue? If so, note its character. Filter, if necessary, 
and test the filtrate with red and blue litmus paper, dip 
a clean platinum wire in the solution and then heat it in 
the Bunsen flame ; observe the color with and without 
blue glass. 

Coal Ash. — Burn a portion of pulverized coal on 
platinum foil until completely ashed (this may take 
some time during which other experiments may be 



12 HOUSEHOLD CHEMISTRY. 

proceeded with). Cool and treat the ash with 5 cc. of 
distilled water, filter, test the filtrate as above, treat the 
residue with warm, dilute hydrochloric acid (HCl), uote 
the character and amount of residue from the latter 
treatment. Test a portion of the hydrochloric acid 
solution in a test-tube as follows : 

1. For lime (CaO). By adding ammonium hydroxide 
(NH^OH) until alkaline, and then an equal bulk of 
ammonium oxalate, and heat to boiling; a white crystalline 
precipitate indicates lime. 

2. For iron (Fe203). Test the remainder of the solu- 
tion for iron, by adding to the test-tube of liquid a few 
drops of ammonium thiocyanate (NH^SCN); a red color 
indicates iron. 

A more elaborate method for analysis of ash is given on 
page II. 

LIQUID FUELS. 

Note. — On account of the highly inflammable nature of 
the following compounds very small amounts must be 
taken for tests, and particular care exercised with the 
use of the naked flame. 

Naphtha and Gasoline. — Pour not more than one or 
two drops of the liquid into a clean dry eight-ounce 
bottle, stir the vapor with a hot glass rod, withdraw the 
rod and apply a light, note the result. 

Pour the same quantity of liquid into a shallow 
porcelain dish and immediately appl}^ a flame, note the 
result and explain the difference in the two phenomena. 



I.IOUID FUELS. 13 

Pour 20 drops of the liquid into a flat watch-glass, 
allow it to stand and note the time of evaporation and 
the quantity of the residue, if any, (Test for the 
presence of water. ) 

Gasoline or naphtha should be neutral; try it with 
delicate litmus paper. 

Kerosene.— Gently heat a small cup half full of the 
oil over hot water, and note the temperature at which 
inflammable vapor is given off ; this is called the flash- 
point and is a valuable indication of the quality of the 
oil. Try the reaction with litmus paper. This compound 
is called an oil; heat a little with strong caustic lye; does 
it make soap ? 

Paraffin. — Heat a small lump of paraffin in a clean, 
dry porcelain dish over a low Bunsen flame and note 
the flash-point as before. Heat a portion with caustic 
lye; does it saponify ? Compare and explain the differ- 
ence in inflammability of gas, kerosene and paraffin. 

Make mixtures of small portions of clean tallow or 
lard with cold gasoline and kerosene and with heated 
paraffin; filter the liquids if not clear and carefully 
evaporate small portions of each on the water-bath. 
Compare the residues with the original substances. Ex- 
plain the action of these solvents in removing grease 
spots. 

Make mixtures of equal quantities of gasoline and 
cold water, kerosene and cold water, and melted paraffin 
and warm water in small corked test-tubes, shake well 



14 HOUSEHOI.D CHEMISTRY. 

and observe their condition. Now allow the tubes to 
rest quietly for ten to fifteen minutes then carefully open 
each and note the condition and position of each. Try 
the specific gravity of kerosene and naphtha with the 
hydrometer. 

WATER. 

Physical Properties. — i. Pour 250 cc. of water into a 
small round-bottomed flask, introduce a thermometer so 
that the bulb is immersed in the liquid and apply heat. 
Note the point at which the thermometer rises when the 
liquid boils quietly. Raise the thermometer just out of 
the liquid. Is there any change ? Does the thermometer 
indicate any higher degree of heat when the water is 
boiling violently ? 

2. Repeat the experiment after dissolving a table- 
spoonful of salt in the water, and note the point at which 
the liquid now boils. Save this liquid for future use. 
(Expts. 7 and 13). 

3. Note the boiling-point of a mixture of equal 
volumes of water and alcohol. 

4. Select a cork which fits the flask, pierce a hole 
through it sufficiently large for a thermometer, and half 
fill the flask with pure water. Boil the liquid and when 
it is in active ebullition, close the flask with the cork 
fitted with the thermometer and withdraw the heat. In 
a few minutes the liquid will cease to boil. Watch the 
thermometer. Pour cold water on the outside of the 
flask until boiling is resumed and watch the thermometer. 
Explain the result. 



WATER. 15 

5. Place a fresh egg in cold distilled water and note 
how much salt must be dissolved in it before the egg 
floats. Explain this phenomenon. 

6. Heat a flask containing about 250 cc. of fresh cold 
tap water over the double boiler or water-bath. Observe 
the air bubbles which collect on the sides of the vessel 
and also the highest temperature of the water obtained 
by this method. 

7. Take a portion of salt solution prepared in Experi- 
ment 2 and boil it down to one-half of its original bulk 
in a small beaker; note with a thermometer the point at 
which it boils, and make frequent readings of the 
thermometer until the desired bulk is reached, then re- 
move the thermometer and allow the liquid to cool 
thoroughly; examine the result with a lens and draw 
what you see. Taste it; does it suggest the original 
salt? 

8. Make a strong solution of cane-sugar in water, 
treat it in the same way as the salt solution, and record 
your results. 

9. Take half a teaspoonful of dry pulverized lime 
(CaO), add to it a teaspoonful of cold water, stir the 
mixture in a porcelain dish with a thermometer, adding 
more water if necessary, record the thermometer readings 
carefully, at the conclusion of the experiment, wash the 
material into a wide-mouthed bottle, fill up with distilled 
water, cork and shake well, let stand until clear and then 
carefully pour away the hquid, add more water, cork and 
shake well again, reserve for future use. The second 



1 6 HOUSEHOLD CHEMISTRY. 

clear solution is called lime-water, (Ca(0H)2), and is much 
used in the laboratory and household as a mild alkali; 
try it with litmus paper, also taste the clear liquid. 

10. Take a tablespoonful of common plaster, mix with 
half the volume of water, in a porcelain dish, stirring as 
before with a thermometer. Read the thermometer as 
the mass hardens. Record the result and compare with 
Experiment 9. 

11. Slowly pour about 10 cc. of strong sulphuric acid 
(H2SO4) into 50 cc. of cold water, stir well with a ther- 
mometer and from time to time record the temperature. 

12. Carefully mix exactly nine volumes of alcohol 
(C2H5OH) and one volume of water ; how many volumes 
result ? Record and explain. 

13. Add two or three drops of the liquid from Experi- 
ment 2 to 100 cc. of water and filter; is any change pro- 
duced ? Now add to the filtrate a few drops of silver 
nitrate (AgNOg) shake well and filter again; note any 
difference. 

14. In eight ounces of water dissolve enough copper 
sulphate to give the resulting liquid a distinct but not 
deep shade. Filter a little of this; what is the result ? 
Reserve the bulk for Experiment 15. What inferences 
do you draw from Experiments 13 and 14? 

15. Distillation of water. 

A. Place on a wire gauze or sand-bath and make 
firm with a clamp, a round-bottomed half-liter flask con- 
taining about 250 cc. of the liquid made in the preceding 
experiment. Insert in the flask a cork fitted wdth a 



WATER. 17 

thermometer and a 45° exit tube and connect this latter 
with a straight tube air condenser. Begin the distilla- 
tion, taking note of the boiling-point of the liquid. 
Examine carefully the distillate, and see if you can 
detect any trace of copper sulphate. Also test with 
phenolphthalein. 

B. Cool the apparatus and add ammonia to the liquid 
in the flask until a clear, deep blue solution is obtained, 
cork and distil again, testing as before. Note the differ- 
ence of behavior of the volatile and non-volatile com- 
pounds. 

Instructions for Making a Simple Filter and Opera- 
ting the Same. — Take a clean colander, lay in it a piece 
of well-boiled muslin and cover with a layer of clean 
boiled sea-sand one to one and a half inches deep. 
Filter the sample of boiled water through this; if once is 
not enough, repeat. 

Some waters are stained brown or yellow by vegetable 
matter and contain finely divided clay; in either case add 
a small quantity of alum (point of the small blade of a 
pen-knife) to the gallon of water, heat slowly to boiling, 
and then filter. 

The muslin and sand may be used many times, but be- 
fore each operation should be treated as follows : Scald 
the cloth and heat the dried sand at least thirty minutes 
in a hot oven. 

Qualitative Examination of Water.— No attempt 
will be made to give methods for quantitative analysis of 



1 8 HOUSEHOLD CHEMISTRY. 

the impurities found in water, but certain qualitative 
tests which will aid in detecting such impurities, when 
present in abnormal amounts, and it is only when found 
in abnormal amounts that the water is open to suspicion. 
The impurities are for the most part harmless in them- 
selves, and a thorough investigation of the surroundings 
and sources of contamination of the water supply, care in 
taking the sample, and other precautions are quite 
essential. 

The tests usually made are : Color and appearance, 
odor and taste, and for the presence of total solids, free 
and albuminoid ammonia, nitrogen as nitrites and 
nitrates, chlorine, temporary and permanent hardness, 
and sometimes phosphates, sulphates, etc. 

Total Solids. — Evaporate to dryness in a clean porcelain 
dish loo cc. (about three ounces) of ordinary drinking- 
water. Examine the residue if any, and notice if it 
blackens on heating. This indicates organic matter. 

Phosphates may be determined at this point by adding 
to the residue a little water, nitric acid and ammonium 
molybdate. If phosphates are present, a yellow crystalline 
precipitate will be formed on heating to body temperature. 

Ammonia. — Two forms of ammonia are looked for in 
water, the ' ' free ammonia' ' and the so-called ' ' albuminoid 
ammonia." 

Free Ammonia. — This is determined by distillation as 
in Experiment 15, omitting the copper sulphate and 
ammonia, and testing each 20 cc. of the distillate with 



WATER. 19 

Nessler's solution which gives a yellow or brown color 
in the presence of ammonia. Continue until a portion is 
found which fails to respond to the test; at this point 
the water is ammonia-free. 

Albuminoid Ammo?iia. — This is ammonia derived from 
organic matter, by means of alkaline permanganate of 
potassium. It may be applied to the water already in 
the flask from which the free ammonia has been ex- 
pelled, or to a fresh sample, in which case you obtain the 
total ammonia and deduct the free ammonia. 

Test. — In either case, add to the water in the distilla- 
tion flask 10 or 15 cc. of alkaline permanganate, boil and 
test the distillates as before with Nessler's solution. 
Note the difference in the amount of ammonia set free. 

Nitrites. — The presence of nitrites in water is supposed 
to be due either to the reduction of nitrates already pres- 
ent in the water by the action of organic matter, or to 
the oxidation of organic nitrogen to nitrite. 

Test. — To about 25 cc. of water in a large test-tube, 
add 5 cc. of freshly prepared mixture of equal parts of 
sulphanilic acid dissolved in acetic acid, and of naphthyl- 
amine acetate dissolved in dilute acetic acid, mix and 
allow to stand for about thirty minutes. If the solution 
becomes pink, the water contains nitrites. Compare with 
a sample of water known to be nitrite-free. 

Chlorine. — Chlorine is found mostly as sodium chloride, 
although other chlorides may be present. 

Test. — Place in a small casserole or porcelain dish 



20 HOUSEHOLD CHEMISTRY. 

about loo cc. of tap water, and in another dish the same 
amount of distilled water. Add to each, two or three 
drops of potassium chromate solution, then add, 
drop by drop, a dilute solution of silver nitrate, 
(N/io) stirring after the addition of each drop, until a 
faint tinge of red appears in the liquid. Obtain the same 
tint in each and note the number of drops of silver nitrate 
used in each case. The difference between the two shows 
the amount of chlorides present. Each drop of silver 
nitrate solution is equivalent to 0.00279 gram of sodium 
chloride. 

Hardness. — By hardness is meant the soap-destroying 
capacity of a water. This property is due principally to 
the fact that calcium and magnesium salts form, with 
ordinary soaps, insoluble compounds or soaps which 
separate as a curd in the water and have no detergent 
value. The hardness of a water may be classified under 
two heads, viz., " Temporary" and " Permanent." 

Temporary Hardness. — Temporary hardness is caused 
by the carbonates of calcium and magnesium held in 
solution by carbonic acid present in the water. Boiling 
expels the carbon dioxide, causing the precipitation of 
calcium and magnesium carbonates. 

Dilute 10 cc. of clear lime-water to 50 cc, place 
the mixture in a large test-tube and pass a rapid current 
of carbon dioxide (made from marble and dilute nitric 
acid) through the liquid. Carefully observe the changes 
in the liquid and when perfectly clear stop the passage of 



WATER. 21 

the gas. Now transfer the liquid to a small low flask 
fitted with stopper and double bent glass tube, the longer 
leg of which should project into a test-tube of lime- 
water. Boil the contents of the flask violently for- some 
minutes, but keep the lime-water cool. Carefully note 
and explain all changes in the contents of flask and tube. 
Finally cool the flask and filter off the clear liquid, pass 
carbon dioxide through this as before, and explain the 
difference in behavior. 

Note the condition of the walls of the flask; why will 
not water remove the crust ? Try dilute acid and watch 
its action. What is the crust ? 

Test. — Place loo cc. of tap water in an eight-ounce 
bottle and add a solution of pure castile soap (lo grams 
dissolved in dilute alcohol), 0.5 cc. at a time, shaking 
thoroughly after each addition, until a lather is formed 
which lasts five minutes. Note the amount of soap 
solution used. 

Now boil 100 cc. of the same sample and repeat the 
test, noting again the amount of soap solution used. The 
difference gives the temporary hardness. 

Permanent Hardness. — Permanent hardness is caused 
by the presence of calcium sulphate and other soluble 
salts of calcium and magnesium, not carbonates, held in 
solution by the solvent action of the water itself; such a 
water cannot be materially softened by boiling but may 
be softened by boiling with sodium carbonate, which 
converts the sulphates, etc., into carbonates and precipi- 
tates them as such. 



22 HOUSEHOI.D CHEMISTRY. 

Dissolve O.I gram of plaster (calcium sulphate) in loo 
cc. of distilled water, pass a rapid current of carbon 
dioxide through the solution and continue at least as 
long as in the case of lime-water. Why is the action not 
the same ? Finally add sodium carbonate solution and 
note the result. Explain. 

Some waters possess both temporary and permanent 
hardness, in which case the total hardness is first deter- 
mined; the water is then boiled and the permanent hard- 
ness determined and then the temporar}^ hardness 
obtained by difference. 

THEATnOSPHERE. 

Composition. — Pure air is mainly composed of four 
parts of nitrogen and one part of oxygen. Other constitu- 
ents occur in small quantities, chief of which are water 
and carbon dioxide. 

Oxygen is a colorless, odorless, tasteless gas, slightly 
soluble in water. It supports combustion, combines with 
all the elements except fluorine, during the operation 
heat and sometimes light is evolved. Oxygen supports 
life and maintains the animal heat by combining with 
the carbon and hydrogen of the food materials. It acts 
as the great disinfectant and deodorizer, destroying many 
bacteria. 

Nitrogen is a colorless, odorless, tasteless gas, almost 
insoluble in water, does not support life or combustion, 
is non-poisonous, and does not cloud clear lime-water. It 
acts as a diluent of the atmospheric oxygen and to some 
extent as food for plant life. 



THK ATMOSPHKRS. 23 

Carbon dioxide is a heavy gas, colorless, tasteless, 
odorless, product of combustion of carbon, but does not 
support life or combustion; is non-poisonous, soluble in 
water, forming carbonic acid (a weak acid), and the 
solution clouds clear lime-water. It is the main food for 
plants, enabling them to produce starch with the aid of 
moisture and sunlight. 600^ + sH^O = CgHjoO^ + 60,. 

The excess of oxygen is returned to the atmosphere. 
Part of the COg dissolves in water and combines with CaO 
(Hme) furnishing shells of moUusks and finally limestone, 
marble, chalk and various other useful carbonates. 

H2O is a colorless, odorless, tasteless liquid at ordinary 
temperature, solid at 32° F., gas at 212° F., volatile at all 
temperatures, without change of composition, is a univer- 
sal solvent, food, does not mix with ordinary fats and is 
more dense. Wood floats in it, metals do not. Iron 
rusts in contact with water. It is neutral, i. e., neither 
acid nor alkaline. 

Oxygen and nitrogen have nearly the same density and 
are mechanically mixed in air, the mixture is maintained 
by constant movement (wind currents). Oxygen with- 
drawn by animals and combustion is replaced by plants, 
some carbon dioxide is withdrawn by rain, which washes 
out other impurities. Excess of moisture is removed by 
fall of temperature, in the form of rain, hail, snow, and 
dew. 

Oxygen, O^. — Pour one inch of alkaline pyrogallol into 
a short, broad test-tube, close with a rubber stopper, in- 
vert and mark the position of the stopper and liquid on a 



24 HOUSEHOI.D CHEMISTRY. 

gum label pasted on the outside of the tube; now shake 
the tube well, invert and open under water, mark the 
level of the water in the tube when open, and explain the 
phenomena. 

Carbon Dioxide, CO^, and Nitrogen, N^. — Fasten one 
inch of Christmas candle to a flat cork, float on a shallow 
dish of lime-water, light the candle and invert a clean 
dry beaker over it; add more lime-water if necessary. 
Describe and explain the result. Try a lighted candle in 
the residual gas; what is the result ? Explain. 

Carbon Dioxide, CO^. — Expose a few drops of lime- 
water on a slide to the air and notice that by the end of 
the lesson it is cloudy. Examine under the microscope 
the rhombohedral crystals of calcium carbonate (CaCOa) 
and draw a diagram of them. 

Hydrogen Sulphide, H^S.— Moisten a filter-paper with 
a solution of acetate of lead and expose to the air until 
the end of the lesson. Notice the black coloration due 
to the formation of lead sulphide. This test works very 
well in gas-lit rooms. 

rioisture. — (i) Expose a strip of dry cobalt chloride 
or cobalt iodide paper to the air and at the end of the 
lesson note the change in color. 

(2) Expose a little calcium chloride (CaCL) on a 
watch-glass, let it remain until the next lesson and note 
any change. 

Dust and Solid Matter. — Put a drop of glycerin on a 



THE ATMOSPHBRK. 25 

slide, place it outside the window and examine under 
the microscope at the next lesson. 

Ferments. — Expose about a teaspoon ful of weak sugar 
solution in a test-tube for about one hour, then loosely 
plug with cotton and examine it at the next lesson as to 
taste, odor and appearance. Place a drop on a slide and 
examine under the microscope. 

Food Principles consist of carbohydrates, fats, 
proteids and mineral matter. 

Carbohydrates. — Compounds containing C, H and O, 
the H and the O in the proportion of 2 : i and the C 6 or 
some multiple. Examples of these compounds are 
starch, cellulose, glucose, sugar, etc. 

Composition of Carbohydrates. — White sugar is used 
since it is the purest commercial carbohydrate. 

1 . Determination of Hydrogen and Oxygen Evolved as 
Water. — Heat about i gram of granulated sugar in a 

clean dry test-tube. Observe the condensation of mois- 
ture in the cooler part of the tube. 

2. Determination of Carbon. — (a) By direct heat, 
continue heating and note the blackening of the mass 
due to freeing of some of the carbon, {b) By dehydra- 
tion, treat about i gram of the sugar in a porcelain 
evaporating dish with a little concentrated sulphuric acid, 
heat gently and note the blackening effect. In this case 
the concentrated sulphuric acid withdraws the hydrogen 
and oxygen in the form of water and leaves the carbon. 



26 HOUSKHOI.D CHEMISTRY. 

3. Determination of Hydrogen and Oxygen in the Form 
of Hydrocarbons, i.e., Tarry Bodies. — Observe the pungent 
odor of the vapors arising from the tube during the heat- 
ing in Experiment 2, (a). This usually condenses on the 
cooler part of the tube in the form of a dark brown 
liquid (caramel). 

(STARCH, C,H,A)..- 
Ordinary Starch Derived from Potatoes or Corn. — i. 

Examine a thin section of potato under the microscope. 
Make a careful drawing of the structure of the cells and 
the granules within. Cover the section with a thin 
glass and introduce a minute trace of iodine solution at 
the edge of the cover glass. Note, and make a colored 
(blue pencil) diagram of the result. 

2. Clean and peel one end of a small potato, rub it on 
an ordinary grater, collect the gratings in a beaker of 
cold water, allow the whole to stand for some minutes 
and examine the sediment. 

3. Gently heat half an inch of dry starch in a clean, dry, 
six-inch test-tube, observe and explain the condensed 
moisture in the cooler part of the tube. Increase the 
heat somewhat and note the odor of the evolved vapor 
and the color of the starch; what does it suggest ? Now 
heat strongly until only a black residue remains; what is 
it? 

4. To a small portion of dry starch in a porcelain 
evaporating dish add a few drops of concentrated 



STARCH. 27 

sulphuric acid; note the result and after a short time heat 
gently and observe again. 

5. Treat a small portion of finely pulverized dry starch 
with cold water, filter a portion and examine the filtrate 
for dissolved material, by evaporating a little on platinum 
foil; also by the iodine test. 

6. Boil the remainder of the starch and water mixture; 
it gelatinizes. Filter some of this and test the clear, cold 
filtrate with iodine, explain. To the remainder when 
cool add a minute portion of iodine solution; it is colored 
blue. Gently heat this and allow to cool again; note the 
result. Now boil for some time, cool, the color does not 
return. Examine under the microscope portions of raw 
and cooked starch, with and without iodine. 

7. To some starch solution in a test-tube add a small 
portion of caustic soda solution (NaOH) and a few drops 
of iodine solution and note the result. Repeat the ex- 
periment using dilute sulphuric acid instead of NaOH. 

8. Add a solution of tannic acid to some starch solu- 
tion. Note the result, also any change effected by heat- 
ing. 

9. Starch, a Colloidal Substance. — Prepare a dialyzer 
as directed and partly fill it with starch solution, then 
stand the whole in a beaker of cold water. After stand- 
ing for some time test the water for starch with iodine 
solution. 

10. Make a verj- weak solution of starch in about 
eight ounces of boiling water ; to half of this solution add 



28 HOUSEHOLD CHEMISTRY. 

20 drops of strong hydrochloric acid and boil until clear, 
replacing the water lost by evaporation. At this point a 
small quantity of the cooled solution should give no blue 
coloration with iodine solution. If this is not the case 
add 10 drops of the same acid and boil some minutes 
longer, or until a small portion gives no test with iodine 
as above. Now neutralize the remainder of the solution 
with sodium carbonate solution. Prepare a Fehling 
solution by mixing 5 cc. of copper sulphate and 5 cc. of 
alkaline Rochelle salt with 20 cc. of distilled water and 
boil the solution exactly two minutes. During this 
period no change should take place in the liquid. Now 
add I or 2 cc. of the neutralized starch solution and boil 
again for two minutes. Note the change in color of the 
liquid and, when cool, the red precipitate of cuprous 
oxide, indicating the presence of a reducing sugar, /. <?., 
glucose. If the changes indicated do not take place, add 
more solution and boil again. 

1 1 . Test the remaining half of the solution in experi- 
ment 10 directly with Fehling' s solution. 

12. Test with unorganized ferments: ptyalin from 
saliva and diastase from malt. Prepare saliva in the 
following way : rinse out the mouth with water, curve 
the tongue so as to place its tip behind the upper incisor 
teeth, then inhale the vapor of ether or even cold air; 
collect the saliva in a small test-tube, dilute with five 
times its volume of water and filter through a filter per- 
forated with the point of a pin. 

Make a starch solution in water, add a few cubic 



DEXTRINE. 29 

centimeters of saliva, warm (not above 40° C.)until clear, 
cool and test with (a) iodine solution, and (d) Fehling's 
solution (maltose). 

To a weak starch solution add about 5 cc. of diastase 
solution and heat to 60° C. As soon as the paste becomes 
clear test a portion with iodine solution and continue 
testing portions until the test fails to give a color 
(maltose). At this stage boil the remainder of the solu- 
tion with about 25 drops of dilute sulphuric acid for 
about ten minutes. Test this with Fehling's solution 
(dextrose). 

Ery throdextrine 1 

DEXTRINE— Achroodextrine 1^ CgH^oOg. 
XMaltodextrine J 

Dextrine or " British Gum" is prepared commercially 
by heating starch moistened with nitric acid. It may be 
prepared more conveniently by heating strong starch 
paste with moderately dilute sulphuric acid, cooling and 
precipitating the dextrine by adding alcohol. 

Try the solubility of dextrine in cold and in boiling 
water. To successive portions of cold dextrine solution 
in test-tubes add : 

1. Iodine solution. 

2. Alcohol. 

3. Caustic potash and iodine solutions. 

4. Sulphuric acid and iodine solutions. 

5. To still another portion add a few drops of ammonia 
and basic acetate of lead; note the result. This is the 
characteristic reaction for gums. 



30 HOUSEHOLD CHEMISTRY. 

6. Test some dextrine solution with Fehling's solu- 
tion; if pure, there will be no reduction. 

7. Test with tannic acid as under starch. 

8. Take about 25 cc. of clear dilute starch solution in 
a small beaker and add 2 or 3 cc. of undiluted saliva, 
keep at body temperature and from time to time filter off 
small portions and test with iodine solution, keeping each 
for comparison. Note the gradual change from blue to 
red to yellow and finally colorless. The stages are: 
Starch, blue; erythrodextrine, red; achroodextrine, 
yellow ; maltodextrine, colorless. 

GLUCOSE— CgH.^Oe, (Dextrose, Levulose, etc.). 

Note the taste and solubility in hot and cold water, 
also the reaction towards iodine solution as with dex- 
trine. 

1. Heat some dry glucose in a clean, dry test-tube; note 
the result and compare with starch and sugar. 

2. To some dry glucose in a porcelain dish add cold 
concentrated sulphuric acid; note the result. After allow- 
ing the test to stand for five minutes, heat gently and 
note the result. Compare with sugar. 

3. Make a syrupy solution of glucose (dextrose) and 
allow it to stand for several days. Do any crystals 
form? Compare with sugar (Expt. 11, p. 33). 

4. Rub up some glucose solution with compressed 
yeast in a porcelain mortar and pour the mixture into a 
short, broad test-tube until full of the liquid. Close the 
test-tube with a perforated cork bearing a glass tube bent 



GLUCOSE. 31 

in the form of the letter J, having the shorter end pro- 
jecting through the cork, and the longer reaching to the 
level of the bottom of the test-tube. This J-tube should 
also be filled with the liquid. Care should be taken that 
there is no air in either tube. Now invert the apparatus 
and let it stand quietly in a warm place for twenty-four 
hours, note the result, explain the collection of bubbles 
or space above the liquid, and hold a drop of clear lime- 
water on a rod over the open tube: why does the drop 
turn milky ? Examine the liquid for alcohol by taste and 
odor and by heating with a few drops of iodine solution 
and caustic potash — odor of iodoform. 

5. To some glucose solution add strong caustic potash 
and heat; note the result. 

6. To 15 or 20 cc. of ammoniacal silver nitrate solution 
(prepared by adding ammonia cautiously to silver nitrate 
until the brown precipitate has almost disappeared; if 
carried too far add a little dilute nitric acid until the 
brown precipitate just reappears) in a clean test-tube, add 
a few drops of glucose solution and caustic potash, heat 
gently and note the result. 

7. Fehling's Solution Test.— In a 100 cc. flask take 5 
cc. of copper sulphate solution and 5 cc. of alkaline 
Rochelle salt, mix and add 20 cc. of distilled water, and 
a few pieces of pumice stone (to prevent bumping), and 
boil for two minutes (during this time no change should 
take place). Now cautiously add a little glucose solution, 
boil vigorously for two minutes, cool and note the result. 
Continue adding glucose and boiling until on cooling a 



32 HOUSEHOLD CHEMISTRY. 

decided change has taken place in the color of the solu- 
tion and a red precipitate is formed. Compare with Ex- 
periment ID under starch. 

8. Test some glucose with Nylander's solution, note 
the result. 

9. Test some weak glucose solution with Barfoed's 
reagent; do not boil. 

10. To 5 cc. of dextrose solution in a test-tube add o.i 
gram of phenyl hydrazine hydrochloride and 0.2 gram of 
sodium acetate (or equal volumes of the two reagents 
may be used), heat the mixture gently until all solids 
dissolve, then keep it in boiling water for fifteen to 
twenty minutes, cool and examine the yellow radiating 
needles of phenyl glucosazone. Compare with lactose 
and maltose. 

SUQAR-C„H,0„. 

1. Examine the crystalline structure of granulated 
sugar. 

2. Roughly determine its solubility in cold water. Is 
the solubility aflfected by heat ? 

3. Boil down sugar solution to dryness and note the 
result. 

4. Drop some concentrated sulphuric acid on dry 
sugar, note the result and compare with starch and glu- 
cose. 

5. Add a saturated sugar solution to 95 per cent, alco- 
hol and note the result. 

6. Boil some sugar solution with Fehling's solution. 
If pure, there should be no reduction. 



SUGAR. 33 

7. Boil some sugar solution with a few drops of con- 
centrated hydrochloric acid, cool, neutralize with sodium 
carbonate and again test with Fehling's solution; note 
the result and compare with glucose. What change has 
taken place in the sugar ? 

8. Test sugar solution with Nylander's solution, before 
and after boiling with acid. 

9. Repeat test with Barfoed's solution as in Experi- 
ment 9 under glucose. 

10. To 10 cc. of sugar solution add some strong caustic 
potash, heat and note the result ; compare with glucose. 

11. Make a hot syrupy solution of sugar and suspend 
in it a piece of glass rod by thread, place aside and allow 
to cool and after a time carefully examine the crystals of 
cane-sugar. 

12. Test for Sucrose. — To 15 cc. of the clear liquid 
add 5 cc. of cobalt nitrate (5 per cent.), and 2 cc. of 
caustic soda (50 per cent.). Sucrose gives an amethyst- 
violet, permanent on heating. Z^^Jir/rf?^^ gives turquoise- 
blue, turning to green on heating. This test may be 
used on milk, honey, preserves, etc. To remove gum or 
dextrine, add ammonia and basic acetate of lead, filter and 
test the filtrate. 

Additional Tests on Sugar.— Boil a strong solution of 
sugar until it has turned brown (caramel), cool, dilute, 
and test some of the liquid with Fehling's solution. 
Filter the balance through bone-black and note the loss of 
color; it may be necessary to pass the liquid through the 
same filter several times. 



34 HOUSEHOI.D CHEMISTRY. 

Viscogen. — To prepare viscogen for restoring the con- 
sistency of pasteurized cream : Two and a half parts by 
weight of a good quaUty of granulated sugar are dissolved 
in five parts of water, and one part of quicklime gradually 
slaked in three parts of water. The resulting milk of 
lime is strained and added to the sugar solution. The 
mixture should be agitated at frequent intervals, and 
after two or three hours allowed to settle until the clear 
liquid can be decanted ofE. This clear liquid (viscogen) 
is the part used and should be kept in well-stoppered 
bottles, as it loses strength and becomes dark-colored 
when exposed to the air. The darkening in color, how- 
ever, does not impair its usefulness. 

CELLULOSE-(C,H,A)»- 
This compound forms the skeleton and covering of the 
plant in the shape of a fine network of interlacing fibers. 
Cellulose is characterized by its extreme insolubility, 
being unacted upon by dilute acids and alkalies. Con- 
centrated sulphuric acid slowly turns paper, a represen- 
tative of cellulose, into hydrocellulose or parchment; ex- 
tremely concentrated caustic potash acts in a similar 
manner. Highly concentrated nitric acid converts 
cellulose into a nitro-compound known as guncotton, 
which is soluble in ether alcohol and known as collodion. 
The cellulose is quite readily dissolved by warming with 
" Schweitzer's reagent," which consists of copper oxide 
dissolved in ammonia, or by a strong solution of zinc 
chloride. Cellulose may be reprecipitated from these 



CELLULOSE. 35 

solutions by adding very dilute acetic acid. Cellulose is 
not colored by the action of iodine solution unless pre- 
viously treated with strong sulphuric acid. 

Various Forms of Cellulose,— Cotton. Cotton occurs 
in flat ribbon-like fibers, easy of detection under the 
microscope. Examine and draw diagrams of various 
samples of cotton fiber and then stain the fiber with di- 
luted iodine solution. Try the solubility of cotton in 
cold concentrated sulphuric acid, afterward dilute with 
water and add iodine solution. 

Paper. — Examine two or three samples of paper under 
the microscope. It is best to use ashless paper, ordinary 
filter-paper and writing paper. Try the iodine test on 
each one of the samples, and note the result. Try the 
solution of small particles of cotton and chemically pure 
paper in warm Schweitzer's reagent, and in saturated 
zinc chloride. 

Crude Fiber. ~Q,e\\.\AQS^ in the form of crude fiber, 
occurring in various forms of plants, remains as an in- 
soluble residue after removal of the starch, proteids, fats, 
etc. , by successive treatments of hot solutions of sulphuric 
acid and caustic potash, followed by water, alcohol, and 
ether in the order named. Conduct the experiment as 
follows : 

Take 3 grams of dry meal or flour, treat with 200 cc. 
of warm 1.25 per cent, sulphuric acid for half an hour. 
Allow the precipitate to settle, and decant or siphon off 
the clear liquid. Treat once or twice with the same bulk 
of water, removing the liquid as before. This operation 



36 HOUSEHOLD CHEMISTRY. 

is to remove starch, dextrine and other saccharides. Now 
treat the residue with 1.25 per cent, caustic potash, same 
as in the acid solution. Wash once or twice with warm 
water, then with alcohol, then with ether. The residue 
is crude cellulose. The caustic potash has for its office 
the removal of the fat and proteids. The alcohol and 
ether remove the last traces of water. 

Experiments on Nitrocellulose or Guncotton. — 

1 . Examine with lens or under microscope. 

2. Compare the combustibility of nitrocellulose and 
ordinary cotton. 

3. Dissolve some guncotton in a mixture of ether and 
alcohol. Pour some of the clear liquid (collodion) on a 
clean sheet of glass. When dry, peel off the coating and 
examine with lens. 

MALTOSE-C„H„0„. 

Maltose does not occur in nature, but is produced dur- 
ing the hydrolysis of starch by unorganized ferments, 
such as diastase, ptylin, etc. 

Preparation of Halt. — Malt is produced during the 
germination of barley and other cereals. Prepare it as fol- 
lows : spread out a thin layer of barley grains ( i table- 
spoonful) on the cover of a small pasteboard box, moisten 
with warm water and keep in a moderately warm place. 
Each grain will soon begin to sprout. When the rootlet 
has grown the length of the grain dry in an oven at a 
low temperature and keep bottled. 



MAI^TOSE. 37 

Make malt extract by grinding the grains coarsely and 
extracting them with loo cc. of warm water. Note the 
taste and odor of the liquid. Keep for future use. 

Preparation of Haltose.— Make a thin starch paste with 
boiling water, cool to 60° and add 10 cc. of malt extract, 
prepared as above, and continue the heating at 60° C. for 
half an hour. From time to time test small portions of the 
liquid with iodine solution; when the liquid fails to react 
blue, cool the balance of the solution, divide in parts and 
test as follows : 

1. Add some of the liquid to strong alcohol, allow it 
to stand, and note the white precipitate of dextrine ; the 
liquid contains maltose. 

2. To 10 cc. of Fehling's solution add a few drops of 
the liquid, boil for two minutes and note the reduction; 
add more of the solution and boil again; repeat until the 
reduction is complete; compare with glucose. 

3. Test with Barfoed's solution but do not boil. 

4. Test with Nylander's solution, boiling as with Ex- 
periment 2. 

5. Apply the fermentation test as under glucose, Ex- 
periment 4. 

6. Test with strong caustic potash as under glucose, 
Experiment 5, 

7. Repeat the phenyl hydrazine test as under glucose, 
Experiment 10. 

LACTOSE P HO HO 

I. Note its hardness and slightly sweet taste, due to 
limited solubility. 



38 HOUSEHOI.D CHEMISTRY. 

2. Try its solubility in water and alcohol. 

3. Treat some dry powdered lactose with concentrated 
sulphuric acid; note the result. 

4. Try the caustic potash reaction. 

5. Apply Fehling's test. 

6. Test with Barfoed's solution in the cold. 

7. Test with Nylander's solution. 

8. Make a weak solution of lactose in water, let it 
stand at least twenty-four hours in a moderately warm 
place, and then test for acid. 

9. Make phenyl hydrazine test as under glucose. 

GLYCOGEN.— QH^A 

Grind up scallops with sand in a mortar, transfer to a 
beaker, add water enough to just cover the mass and 
boil. This dissolves the glycogen and partially precipi- 
tates the proteids, which are now completely precipitated 
by adding a few drops of acetic acid. Filter and to the 
filtrate add alcohol (95 per cent. ) until glycogen comes 
down as a white precipitate. Allow to settle, decant off 
the clear liquid, and filter the remainder. 

To portions of the solid glycogen left on the paper try 
the following tests : 

1. Solubility in water, and look for opalescence. 

2. Solubility in 10 per cent, sodium chloride solution. 

3. Solubility in hydrochloric acid. 

4. Solubility in caustic potash. 

5. Iodine solution. 

6. Boil in a beaker for fifteen minutes with 20 drops of 



FATS. 39 

dilute hydrochloric acid, then neutralize with sodium 
carbonate and test with Fehling's solution. What 
change has taken place ? 

7. Glycogen is soluble in alcohol from o to 60 per cent. 
Glycogen is insoluble in alcohol from 60 to 100 per cent. 

FATS. 

There is much confusion in regard to the composition 
of the various bodies commonly known as fats. At least 
two distinct classes are recognized, viz., (i)true fats or 
glycerides, containing carbon, hydrogen and oxygen, 
essentially in the form of fatty acid and glycerine, and 
existing as liquids and solids. (2) Hydrocarbons con- 
taining only carbon and hydrogen, in very simple forms 
of combination, but existing as gases, liquids and solids. 
The first always yield some of their carbon in the free 
state on heating, the latter rarely. Confirm this by 
burning small portions of tallow and of kerosene in sepa- 
rate porcelain dishes over the Bunsen burner. 

Composition of Qlycerides.-Determination of hydrogen 
and oxygen in the form of water. Boil 20 to 25 drops of 
clear olive oil in a clean dry, test-tube; note the deposi- 
tion of moisture in the cooler part of the tube. Some of 
the water running back will cause the fat to crackle. 

Determination of QIycerine,C3H5(OH)3. —Continue the 
heating until dense fumes arise from the boiling liquid; 
this is due to acrolein, formed from the heated glycerine. 
Cool the tube and contents and reserve for the next step. 



40 HOUSEHOLD CHEMISTRY. 

Determination of Carbon and Hydrogen as Hydro- 
carbons. — Pour the cold tube contents into a clean, dry 
porcelain dish and heat slowly but strongly over a low 
flame. Note the gradual darkening of the liquid due to 
freeing of some carbon and the tarry coat on the rim of 
the dish due to liquid hydrocarbons. Hold a lighted 
match over the dish and note the character of the 
inflammable vapor, due to gaseous hydrocarbons. Ex- 
tinguish the flame and continue the heating until only a 
black residue remains; this is carbon; prove it by burning 
it off. 

Preparation of Pure Fat from Natural Sources. — 

Weigh out lo grams of beef suet cut up in small pieces. 
Place in a small evaporating dish and heat cautiously, 
stir with a thermometer and do not allow the tempera- 
ture to rise above 130° C. (What causes the spattering?) 
When the spattering has ceased strain through muslin 
into a porcelain dish, squeeze out the cloth and reserve 
for tests on fats. Transfer the residue to a small mortar, 
add 5 cc. of strong alcohol, and grind well. Pour this 
mixture into a small flask, wash out the mortar with 
alcohol and add the washings to the flask, finally close 
the flask with a cork, bearing a condenser tube 24 inches 
long, support on a ring-stand over a water-bath and boil 
for ten minutes. When the suspended matter has 
settled, uncork the flask and pour the clear liquid on a 
small filter, allowing the filtrate to run into a large test- 
tube. To the residue in the flask add 20 cc. of ether, 
insert the cork and condenser and cautiously heat over 



FATS. 41 

hot water for five minutes, then transfer the entire con- 
tents of the flask to a small muslin filter and collect the 
filtrate in the same tube as before. Wash this last resi- 
due with a little ether and squeeze out the ether, spread 
out on the muslin and allow it to dry and test the residue 
for proteid with Millon's reagent. Close the test-tube 
with a loose cotton plug and allow it to stand until 
crystals deposit from the liquid; examine these under the 
microscope and draw a diagram of them. 

Make the following tests on the rendered fat : 

1. Place a small piece of fat in a clean, dry test-tube, 
add 5 cc. of alcohol and heat until the fat melts, then test 
with delicate litmus paper. 

2. Place a small piece of fat on a filter-paper and heat 
until the fat melts; note the result. 

3. Rub up a small piece of fat in a mortar with some 
acid potassium sulphate, transfer to a clean, dry test-tube 
and heat cautiously; note the peculiar disagreeable odor 
of acrolein due to the dehydration of the glycerine. What 
does it suggest ? 

4. Warm a small piece of fat in a test-tube with strong 
sodium carbonate, shake well, noting the result and allow 
the mixture to stand. What happens ? 

5. Saponification. — Boil a portion of pure fat in a small 
flask with strong alcoholic potash solution. Replace the 
liquid lost by evaporation with hot water. As the 
evaporation proceeds, the mixture should become homo- 
geneous. If it does not, add a little more potash and 
boil again but avoid any large excess. A drop of the hot 



42 HOUSKHOI.D CHEMISTRY. 

liquid should dissolve completely in hot water (soap). 
When saponified boil until the alcohol is removed, cool 
the liquid and divide into three portions. 

A. To one portion add a rather strong solution of salt; 
notice the curdy precipitate (soap). Filter off this pre- 
cipitate, dissolve it in some fresh water and boil down 
some of the filtrate. Note any change in color or odor 
and finally when quite concentrated pour a few drops of 
the thick liquid on a platinum foil, add bisulphate of 
potassium, evaporate to dryness and ignite gently. Note 
the odor and blackening; what does it suggest ? (Odor 
of frying fat.) What are the white crystals? 

B. Acidify another portion of the dissolved soap with 
dilute sulphuric acid and note the curdy precipitate, 
which is insoluble in water but soluble in warm alcohol, 
(fatty acids), boil the mixture until clear, filter and 
reserve for future use. 

C. Add a solution of lime-water to another portion 
of the soap solution and notice the greasy precipitate, 
which is insoluble in warm water and alcohol (lime soap, 
produced by hard water). 

6. Test the solubility of the fatty acids prepared in ex- 
periment 5 B with alcohol, and sodium carbonate solu- 
tion. 

7. Introduce small portions of fat into separate tubes 
containing water and alcohol, warm gently and note the 
result. 

8. Emulsification Experiments. — Shake together a few 
centimeters of cod-liver oil and dilute sodium carbonate. 



FATS. 43 

Notice the resulting white mass which is called an emul- 
sion; what well known liquid is similar in appearance? 
Examine two or three drops of this emulsion under the 
microscope and note the character of the compound. 

Repeat the same experiment, using a few drops of olive 
oil and a solution of albumen. 

The phenomena observed in these two experiments 
throw light upon the digestion of fatty substances. 

Heat a small quantity of lard or tallow for some time 
in an evaporating dish with lead oxide, PbO, and a little 
water, filter off the watery liquid and evaporate a small 
quantity on a platinum foil. Note the characteristic odor 
of acrolein, proving the presence of glycerine. 

I. Lard. II. Oliveor Cottonseed Oil. III. Tallow.— 

Determine the melting-point of these four substances 
by filling 2-ounce medicine vials half full of the liquid 
fats. Introduce a thermometer and cork in such a way 
that the bulb of the thermometer is enveloped in the 
fat. Now chill until the mass becomes solid, lay the 
bottle in a horizontal position in a warm place and closely 
watch for the point when the fat just becomes liquid (do 
not heat too rapidly), and observe the temperature. This 
is the melting-point. 

Tests for Cotton-seed Oils. Becchi' s Test. — To 5 cc. of 
the oil in a test-tube add an equal volume of silver 
nitrate dissolved in alcohol (i percent, solution), close 
the test-tube and keep it in boiling water for ten to 
fifteen minutes. A darkening of the mixture indicates 
cotton-seed oil. 



44 HOUSEHOI.D CHEMISTRY. 

Halphen' s Test. — To 5 cc. of the oil in a test-tube add 
5 cc. of amyl alcohol and 5 cc. of carbon disulphide con- 
taining a little free sulphur. Place the tube in a beaker 
of cold water and bring the water to a boil and allow the 
tube to remain for twenty minutes. A red coloration 
indicates cotton-seed oil. This is a very delicate test. 

Preparation of Cold- Hade Soap. Lye. — Dissolve the 
contents of one can of Babbitt's potash (i lb.) in one 
quart of cold water. This gives a solution of about 40° 
B6. 

Fat. — Tallow rendered according to directions given on 
page 43. Heat the fat until it is just liquid and add 
slowly with constant stirring lye equal in amount to one- 
half the fat taken. Stir it thoroughly until homogeneous 
and pour into a vShallow pasteboard box. Allow it to 
stand for at least twenty- four hours, and then test for 
free fat and free alkali as follows : 

For Free Fat. — Shake a few shavings of the soap in a 
corked test-tube with cold gasoline, filter into a convex 
glass and evaporate off the gasoline over warm water. A 
greasy residue indicates unsaponified fat. 

For Free Alkali. — Shake a few shavings of the soap in 
a corked test-tube with warm alcohol (95 per cent.), 
filter and add to the clear liquid a few drops of 
phenolphthalein; a red color indicates free alkali. 

PROTEIN BODIES. 

These compounds always contain carbon, hydrogen. 



PROTEIN BODIES. 



45 



oxygen and nitrogen, sulphur, sometimes phosphorus, 
iron, etc. They may be classed as follows : 



' Simple. 



Protein bodies - 



f Albumen 
t Globulin 

f Coagulated forms 
Acid albumen 

'Proteids ■{ Derived... -l Alkali albumen 

Albumose 
Peptone 

I Compound.. Nucleoproteid 

Albuminoids \ Gelatine, from tissues and bones 
^ Keratin, from hair 



Composition of Proteins. — 

1. Determination of Nitrogen as Ammonia. — Mix some 
dried albumen with lime and moisten sufficiently to roll 
into small .balls with the fingers. Place two or three of 
these balls in a dry test-tube, heat and hold in the vapors 
a piece of moistened red litmus paper, note the result. 
Let the paper dry and note the change. 

2. Determination of Sulphur as Hydrogen Sulphide. — 
Test the fumes with a piece of filter-paper moistened 
with lead acetate and note the result. 

3. Determination of Hydrogen and Oxygen as Water. — 
Observe the condensation of water in the cooler part of 
the tube. 

4. Determination of Carbon. — Observe the blackening 
effect produced by the freeing of the carbon. 



46 HOUSEHOLD CHEMISTRY. 

Tests on Simple Proteids. — 

Preparation of Egg Albumeji. — Carefully break a fresh 
egg, allow the clear white to run into a porcelain dish 
and set the yolk aside for future use. Cut the white 
with scissors or grind with glass powder and place a 
small portion in a wide-mouthed stoppered bottle, add ten 
volumes of distilled water, shake until it froths and invert 
over a small casserole of water. When the froth and 
proteid particles float on the surface, carefully withdraw 
the cork and allow some of the liquid to mix with the 
water in the casserole. The liquid will probably be 
opalescent, due to traces of globulin; if strongly so, filter 
through cloth, test the fluid with litmus paper and if 
alkaline neutralize with weak acetic acid (2 per cent.) 

Tests. — I. To a small portion of the filtered liquid add 
strong nitric acid. This forms a white precipitate which 
turns yellow on heating; now cool and add ammonia — it 
becomes orange. Compare with spots on the skin or 
woolen cloth produced with nitric acid. 

2. Milloii' s Test. — To a small portion of the solution 
add Millon's reagent and heat. This forms a white 
precipitate which turns red on cooling, or gives a red 
color if only a trace of proteid is present. 

3. Precipitation Tests. — To seven portions of the solu- 
tion in separate test-tubes add : 

a. Lead acetate. 

b. Mercuric chloride. 

c. Tannic acid. 



PROTEIN BODIES. 47 

d. Alcohol. 

e. Acetic acid and potassium ferrocyanide. 

/. An excess of dry crystallized ammonium sulphate 
(shake vigorously ) . 
g. Dry sodium chloride or magnesium sulphate. 

In each of the above tests carefully note the character 
and color of the precipitates. 

4. Coagulation by Heat. — Heat some of the fluid to boil- 
ing and add, drop b}^ drop, very dilute acetic acid as long 
as a precipitate forms; note that this precipitate does not 
appear unless the solution is acid. Attempt to filter some 
of the albumen through a wet filter-paper; prove by one 
of the above tests that no proteid is in the filtrate. Re- 
peat the above test, using first undiluted ^%% albumen and 
second a very dilute solution (i cc. to 100 cc. of water.) 

5. Heller' s Test. — Place some strong nitric acid in a 
test-tube and allow a solution of albumen to flow gently 
down the side of the tube; a white ring of precipitated 
albumen forms at the junction. 

6. To I inch of 10 per cent, caustic soda or potash add 
dilute copper sulphate, drop by drop, until a faint blue 
color but no precipitate appears in the liquid; now add 
the proteid solution. A violet color indicates proteid; a 
pink, peptone. 

7. Metaphosphoric Acid Test. — To a solution of albu- 
men add a very little cold freshly prepared meta- 
phosphoric acid and note the precipitate formed. 

8. hidiffusibility . — Place some of the solution in a 



48 HOUSEHOLD CHEMISTRY. 

dialyzer of parchment paper and suspend the whole in a 
beaker of distilled water. Test the water subsequentl}- 
for chlorides with silver nitrate and also for proteids by 
the biuret test. 

GLOBULINS. 
Globulin from White of Egg.— Saturate some of the 
ordinary solution with magnesium sulphate, grinding the 
mass in a mortar. Observe the precipitate of globulin, 
filter and test the filtrate for proteid, now pour water 
through the insoluble mass on the filter and test the ex- 
tract for proteid. Explain. The yield of globulins 
obtained from this source is very small. 

Globulin from Hemp Seed. — Extract dry, ground 
hemp seed with 5 per cent, salt solution, heating the 
mixture gently but not above 50° C; filter and test the 
clear filtrate as follows : 

1. Heat to coagulating point ; what is it ? 

2. Add sodium chloride to saturation, filter and test 
the precipitate with nitric acid. 

3. Make the biuret test for proteid on some of the 
saline solution, and also on the precipitate from No. 2. 

Important Properties of Albumens and Globulins. — 

Albumens are soluble in water and saturated solutions of 
sodium chloride and magnesium sulphate and insoluble 
in saturated solution of ammonium sulphate. Globulins 
are insoluble in water, soluble in weak solutions of 
sodium chloride (5 to 10 percent. ), insoluble in saturated 
solutions of sodium chloride, magnesium sulphate, and 
ammonium sulphate. 



GLOBUI.INS. 49 

Alkali Albumen. — Treat undiluted white of egg with 
strong alkali, note the clear jelly-like mass which results. 
Dilute some of this with water and try coagulating by 
heat, finally exactly neutralize with acetic acid and 
observe the precipitate of alkali albumen. Test some of 
this by the biuret test. Weaker solutions of albumen 
are converted by treating with a few drops of very weak 
alkali (o.i per cent.) at ioo° F. , for some minutes. 

Acid Albumen. — Treat undiluted white of egg with 
concentrated hydrochloric acid and heat, resulting in a 
beautiful violet-blue solution. Dilute some of this and 
try the coagulation test ; now neutralize with dilute 
alkali and note the precipitate of acid albumen. Test 
some of this by the biuret test. Repeat the treatment of 
white of egg, using strong acetic acid. Also try heating 
weaker solutions with a very few drops of highly dilute 
sulphuric acid (o.i per cent, at ioo° F. for some time). 

Saturate portions of the solutions of acid and alkali 
albumen with sodium chloride and record the results. 

Fibrin from Blood (a globulin like substance). — Re- 
peat the tests made on coagulated egg albumen and re- 
cord the results. 

Albumose and Peptone. — The action of pepsin is hy- 
drolytic and produces both albumose and peptone — a case 
similar to the production of dextrine and glucose from 
starch. 

Preparation of Albumose and Peptone. — Coagulate egg 
albumen by heat. Place some of the coagulum in four 
test-tubes and treat as follows : 



50 HOUSEHOLD CHKMISTRY. 

1 . Add water and a very small portion of highly dilute 
hydrochloric acid (0.2 per cent). 

2. Add water and a very small amount of pepsin solu- 
tion. 

3. Add both pepsin and hydrochloric acid. 

4. Add a few drops of 10 per cent, salt solution. 
Place all four tubes in a beaker of cold water, heat to 

body temperature and note the time they take to clear; 
also observe whether the mass swells; finally filter all 
four and test the clear filtrate by biuret test. 

GELATINE. 

B}^ prolonged boiling with water, gelatine is produced 
from collagen, which is a protein occurring in the con- 
nective tissue. 

Place small pieces of gelatine in contact with cold 
water and note any change which takes place, then 
slowly heat the mixture to boiling; does it coagulate ? 
Cool a portion of the liquid; what happens? Test the 
remainder of the warm solution, divided into seven parts 
with : 

1. Hydrochloric acid. 

2. Acetic acid. 

3. Alum. 

4. Basic acetate of lead. 

5. Salt and tannin. 

6. Heller's test. 

7. Biuret test. 



TESTS ON MII,K. 



51 



Acid and Alkali Albumen and Gelatine Peptone 

1. Boil some gelatine for several minutes with dilute 
hydrochloric acid, cool and note that it does not set. 

2. Repeat the test, using alkali in place of acid. 

3. Treat some gelatine jelly with 0.2 per cent, hydro- 
chloric acid and pepsin at body temperature, finally test- 
ing the liquid for peptone. 

TESTS ON MILK. 

Use Fresh Milk — Try the reaction with test-paper. 
Allow a 6-inch test-tube full of milk to stand quietly for 
about an hour and note the result. Fill a tall cylinder 
with milk and determine the specific gravity with a 
lactometer and record the result. Determine the specific 
gravity of skimmed milk, then add water until the 
original gravity is restored. Explain this phenomenon. 
Is cream lighter or heavier than milk ? 

Examine a drop of milk under the microscope, add a 
drop of dilute caustic soda, and re-examine. Heat some 
milk to boiling ; no coagulum appears, only a thin skim. 

Pioscope Test.— Place a drop or two of fresh well- 
mixed milk on the center of the hard rubber disc, cover 
carefully with the glass plate and compare with the 
standard scale of colors. 

Lactoscope Test — Use Feser's lactoscope. Fill the 
pipette with milk, allow it to run into the cy Under. Now 
cautiously add water, shaking after each addition, until 
the marks on the cloudy glass rod are just visible through 



52 HOUSEHOI.D CHEMISTRY. 

the liquid, read off and record the percentage of fat at 
the level of the liquid. 

Caseinogen. — Dilute sorne milk with lo volumes of 
water, and carefully neutralize with dilute acetic or hy- 
drochloric acid ; no precipitate appears; why? Cautiously 
add more acid until there is a copious precipitate (case- 
inogen). This action is hastened by heating to 70° C. 
Filter through a moist fluted paper, the filtrate should be 
clear ; set aside the precipitate and divide the filtrate into 
three equal portions. A, B and C. 

A. Boil this portion to precipitate lactalbumen, filter, 
test filtrate for lactose. Try biuret test on the precipi- 
tate. 

B. Add potassium ferrocyanide and acetic acid, a pre- 
cipitate of lactalbumen. 

C. Test for lactose without removing soluble albumen. 

Residue of Casein and Fat on Filter-paper. — Wash 
with water and then with alcohol and finally treat residue 
with a mixture of ether and alcohol, filter and evaporate 
some of the clear liquid; note the greasy residue of butter 
fat. 

Action of Salts. — Sodium chloride or magnesium 
sulphate: saturate a portion of milk with common salt; 
note the precipitate of caseinogen and fat floating on the 
liquid, filter and wash. The washings should run into a 
separate vessel; to this add an excess of acetic acid to 
precipitate caseinogen; why does the caseinogen go back 
into solution ? 



ADDITIONAL TKSTS ON MILK. 53 

Clot milk with rennet, using boiled and unboiled milk 
and note any differences. Curdle milk with the aid of 
heat (40° C.) and acetic acid, filter, dissolve one portion 
of the curd in weak caustic soda, and grind the balance 
in a mortar with lime-water, filter, add rennet to both 
and heat to body temperature; note the results, especially 
the action of lime-water. 

Test some of the curd with pepsin hydrochloric acid, 
and heat; note the result. 

Salts. — Test the clear filtrate as follows : 

1. Chlorides. — Add silver nitrate and nitric acid; it 
gives a white curdy precipitate soluble in ammonia. 

2. Sulphates. — Add hydrochloric acid and barium 
chloride; it gives a white crystalline precipitate. 

3. Phosphates. — Add magnesia mixture; it gives a 
white crystalline precipitate. 

ADDITIONAL TESTS ON fllLK. 

1. Heat one cup of milk to the boiling-point, boil 
gently for five minutes, cool to 40° C. and add rennet ; 
note the character and amount of curd. 

2. Boil one cup of milk for fifteen to twenty minutes, 
replacing any liquid lost during evaporation by hot dis- 
tilled water ; cool to 40° C, add rennet, note character 
and amount of curd. 

3. To one cup of milk add i to 2 cc. of ammonium 
oxalate solution (precipitant for lime), boil for two or 
three minutes, cool to 40° C. and add rennet ; note char- 



54 HOUSEHOI^D CHKMISTRY. 

acter and amount of curd, if any ; finally add lime-water 
equal in bulk to the original milk, warm to 40° and note 
the result. 

4. Note the effect of rennet on separate portions of 
milk heated to 20°, 30°, 50°, and 80° C. 

5. Boil rennet in water and then add to milk ; note 
the result. 

Tabulate the results of the above tests. 

Butter-Fats.— Fill a test-tube half full of milk, add 
half a volume of caustic soda, and a little ether, cork and 
shake well, then place in a beaker of warm water and 
allow to remain quiet. In a few minutes note the layer 
of oil and ether floating on the surface. Remove some 
of this with a pipetie and evaporate at a low heat ; note 
the butter residue. 

Souring. — Place some milk in a wide-mouthed bottle, 
allow it to stand in a warm place for some days or until 
sour, filter ofi" the curd and test the filtrate for lactose. 
Explain the change which has taken place. 

Skimmed Milk. — Take a small portion of skimmed 
milk, try its reaction with litmus paper. If not already 
alkaline, make so with sodium carbonate and heat to 
boiling. Note the result. Make another portion acid 
with hydrochloric acid, heat, and note the result. 

To a solution of skimmed milk which is slightly warm 
add rennet, stir well and allow to remain for some time. 
Note the peculiar character of the curd; cut the curd and 
note the thin watery liquid which runs from it (whey). 



ADDITIONAI. TKSTS ON MILK. 55 

Collect a sufficient quantity of the whey and test it for 
soluble proteid (lactalbumen). Further notice the sweet 
taste of the whey, due to lactose (milk-sugar), and its 
effect on boiling Fehling's solution. 

Butter. — Specific tests. 

Melt about a teaspoonful of butter with ten times the 
volume of warm water, stir the mixture vigorously and 
then chill it by standing it in ice water. Punch two 
holes in the cake of solid fat and decant off the liquid. 
Preserve some of this liquid for a test. Taste a portion. 
Test with litmus paper. To a small portion of the solu- 
tion add a few drops of nitrate of silver and note the re- 
sult. Continue the washing operation two or three 
times until the final filtrate is quite clear. Note any 
difference between the first and last filtrates in respect to 
taste, and test with litmus and silver nitrate. Carefully 
dry some of the chilled fat between layers of filter-paper. 
Melt the fat in hot water and filter it through dry paper. 
Preserve this fat for future work. 

Now wash the paper with a very small portion of cold 
gasoline until a drop of the washings evaporated on 
paper leaves no greasy stain, dry and note the character 
of the residue on the filter-paper. Cautiously heat some 
of the residue in a test-tube with lime; observe the odor 
produced and hold in the fumes a piece of moistened red 
litmus paper and note the result. 

Place a drop of the butter-fat first on water and then 
on 95 per cent, alcohol ; note whether it floats or sinks in 
either liquid. Mix a small portion of the fat with 



56 HOUSEHOLD CHEMISTRY. 

potassium or sodium bisulphate, heat on a platinum foil, 
and note the peculiar disagreeable odor (acrolein). Com- 
pare the odor of this compound with the odor produced 
by treating glycerine in the same way. 

Cheese. — Take a sample of any well-cured cheese, 
grind some of it in warm water, filter and reserve the 
residue. 

Divide the filtrate into six parts and test as follows : 

1. For acidity with litmus paper. 

2. For soluble proteid. 

3. Neutralize for acid or alkali albumen. 

4. For peptone. 

5. For soluble mineral matter, i. e., chlorides, sul- 
phates, etc. 

6. For ammonia and sulphides. 

Now extract the residue several times with the same 
portion of warm alcohol and test the extract for fatty 
acids. Again extract the residue with warm ether 
several times and evaporate some of the clear ethereal 
liquid over warm water; is the residue greasy? 

Divide the extracted residue into two parts and test as 
follows : 

1. For insoluble proteid. 

2. Burn to white or gray ash and test for insoluble 
mineral matter, phosphates, lime, etc. 

During the incineration, hold pieces of moistened red 
litmus and lead acetate paper in the fumes and record the 
results. 



TESTS ON EGGS. 

A. Yolk. — Place one-half the yolk of a fresh egg in a 
broad six-inch test-tube, add twice the bulk of ether, 
cork and shake well, allow the tube to rest until the con- 
tents separate into two or more layers, uncork the tube 
carefully and pour off the upper (ether) layer into a 
clean, porcelain dish and reserve for further work. Now 
add another portion of ether to the tube, cork, shake and 
allow to stand until settled, pour off the clear liquid as 
before, adding it to the clear ether solution obtained in 
the first operation. Repeat these washings at least four 
times or until the residue in the tube is white or nearly 
so. Dry over hot water and reserve for future test, it is 
essentially vitellin. 

Evaporate the combined ether extracts over warm 
water-bath (no open flame). When the ether has passed 
off, note the yellow liquid oil similar to melted butter. 

Put a drop or two in water; notice that it does not mix 
and is oily. Now add two or three drops of concentrated 
nitric acid to the contents of the dish, and note the 
change of color. Then add a few drops of water and 
ammonium thiocyanate; red color indicates iron. 

Vitellin. — Test the solubility in water and lo per cent, 
salt solution ; filter these solutions if any are obtained and 
test them as follows : 

1. Biuret. 

2. Heller's or Millon's. 

B. See tests under albumen, page 51. 



58 HOUSEHOLD CHEMISTRY. 

C. Shell— 

1. Kxamine a portion of the shell under the low power 
of a microscope ; note the physical character. Treat a 
portion of the shell with dilute silicate of soda solution ; 
when dry, examine as before. (Silicate of soda is used 
for preserving eggs). 

2. Boil an ^^'g with an unbroken shell for ten minutes 
with a dilute aqueous solution of any coal-tar dye, cool, 
carefully remove the shell, note the staining of the 
coagulated white, and explain. 

3. Crush the shell, thoroughly extract with warm 
water, dissolve the extracted mass with dilute hydro- 
chloric acid, and note the effervescence. Hold in the 
fumes a drop of lime-water on the end of a glass rod and 
note the clouding. What gas is formed? Now filter, 
make slightly alkaline wuth ammonia, add ammonium 
oxalate and note the white precipitate of calcium oxalate, 
insoluble in acetic acid. From the data found, give the 
composition of the shell and the changes which have 
taken place. 

4. Allow an ^%% to stand in strong vinegar for several 
hours, remove, wash in one change of water, and note the 
peculiar condition of the ^%z. Examine the acid liquid 
as in the preceding experiment. 

5. Examine equal portions of the yolk and white of 
^%% for sulphur by the lime and lead acetate method 
given under proteids. Which do you think contains the 
greater amount of sulphur ? 



MUSCLE. 

Cut off the exterior of a piece of lean meat, test the 
interior with litmus paper and note the reaction. Then 
cut the meat in small pieces with scissors and grind these 
in a mortar with clean, dry sand. Take one-half of the 
ground mass and extract in a beaker of cold water, stir- 
ring every few minutes. Allow the extraction to pro- 
ceed for half an hour ; while this is proceeding, take the 
balance of the ground mass and extract with i o per cent, 
salt solution, stirring as before. Finally pour off and 
filter the watery extract ; take about one-fourth of the 
liquid and divide into four parts, testing each as follows : 

1. Biuret. 

2. Heat. 

3. Add crystals of ammonium sulphate to saturation. 

4. Boil with a few drops of hydrochloric acid, neutral- 
ize with caustic potash, add Fehling's solution and boil ; 
note the result (glycogen, CgHioO^). 

The balance of the solution, three-fourthsof the whole, 
will yield creatin if treated as follows : Boil, filter, to 
the filtrate add lead acetate as long as a precipitate forms, 
filter again, through the filtrate pass hydrogen sulphide, 
filter again, slowly concentrate the filtrate and examine 
under the microscope — knife-rest crystals. 

Saline solution must stand at least one hour (better 
twenty-four); after standing, pour off the solution of 
globulins and test as follows : 

1. Pour a few drops into a large excess of water, 



6o HOUSKHOLD CHEMISTRY. 

milky deposit of myosin, soluble in strong salt solution. 

2. Heat short of boiling and note the result; cool, and 
test the liquid with litmus paper. 

3. Saturate with salt, precipitate of myosin, filter, dis- 
solve, precipitate in weak salt solution, and make Biuret 
test. 

4. Suspend a crystal of rock salt in the solution and 
note the result. 

Make meat extract by steeping lean meat in cold saline 
water, gradually heating to a boil and finally under 
slight pressure. Pour off the liquid, cool, remove the 
fat, dissolve some of the jelly in warm water and compare 
with lyiebig's or Armour's meat extracts by the follow- 
ing tests : 

1. Biuret. 

2. Glycogen test. 

3. Creatinin, Weyl's test: add a very dilute solution 
of sodium nitroprusside and, cautiously, caustic soda — 
ruby-red color. 

4. Examine the solid extract under the microscope and 
note the cubical crystals of salt and knife-rest forms of 
creatin. 

Make a water solution of meat (without washing out 
the blood), heat to coagulate the proteid and filter. Add 
a few drops of concentrated nitric acid and evaporate the 
liquid to dryness ; cool and take up with water; if cloudy, 
filter; divide into five parts and test as follows : 

I. For chlorides with nitric acid and silver nitrate — 
white precipitate. 



MUSCLE. 6 1 

2. For sulphates with hydrochloric acid and barium 
chloride — white precipitate. 

3. For phosphates with nitric acid and ammonium 
molybdate — yellow precipitate or color. 

4. For calcium with ammonium hydroxide and ammo- 
nium oxalate — white precipitate. 

5. For iron with hydrochloric acid and ammonium 
thiocyanate — red color. 

Experiments in Cooking Tough fleat. — Cut the meat 
in cubes weighing about four ounces. Treat one piece 
in boiling water (one pint) covered and add hot water 
from time to time to prevent concentration ; make this 
test with and without salt. 

Preserve the liquids carefully, evaporate 100 cc. of 
each for total solids, weigh, ignite off organic matter and 
weigh mineral residue ; test this for potassium, sodium, 
calcium, magnesium and iron, phosphates, chlorides and 
sulphates. 

Carefully record the physical condition of the pieces of 
meat; note their palatabality. 

Treat two pieces of the same meat to cold bath of 
vinegar and water for twenty-four hours, then cook as 
before with and without salt. Record results as above. 

In using salt, take the best dry salt and determine the 
weights of various level spoonfuls ;' use these factors. 

Composition of Bone.— Procure raw shin-bones of beef 
and have them well scraped and sawed into one-inch sec- 
tions. Treat these sections for two or three hours under 
slight pressure in a soup digester with the least possible 



62 HOUSEHOLD CHEMISTRY. 

amount of water. Pass the extract through cheese- 
cloth, filter into a tall glass cylinder, and allow it to cool. 

A. Tests on the Extracted Bone. — 

1. Dry and examine the bone, comparing its condition 
before and after treatment. 

2. Break the extracted bone into small pieces and char 
a few of these in a small porcelain dish. Note the dis- 
agreeable odor of the fumes evolved in the operation. 
When these have ceased, allow the mass to cool some- 
what and then transfer them to a clean dry, test-tube and 
cork tightly. 

Note. — This material is known as bone-black and is 
largely used for decolorizing many food products, 
notably sugar. 

3. When the contents of the test-tube are thoroughly 
cool, pulverize them in a mortar. Test the decolorizing 
power by placing a portion of the bone-black in a dry 
filter-paper and passing diluted molasses through it, re- 
peating the operation if necessary and comparing with 
the unfiltered portion. 

4. Ignite another portion of the bone-black on a plat- 
inum foil until a white ash is obtained. Dissolve this 
ash in dilute nitric acid and test for lime and phosphoric 
acid in the usual manner. 

B. Tests on the Water Extract.— 

1 . When thoroughly cool remove the layer of fat and 
compare with tallow obtained in a previous experiment. 

2. Make tests for proteid and gelatine on the balance 
of the extract. 



WHEAT FLOURS. 

Four samples to be tested; viz., white bread, baker's, 
maccaroni and whole wheat flour. 

Examine small portions of each under the microscope 
as in lesson under starch. Make paste, stain with 
iodine and examine again. 

Take twenty-five grams of the sample, mix on a porcelain 
or glass plate with the least amount of water to make a 
stiff dough, measure the quantity used and do the mixing 
with a flexible steel knife. Do not handle the dough 
with the fingers. 

Transfer the masses of dough to four separate pieces 
of well-washed muslin, taking care to clean the mixing 
surface and knife thoroughly in each case ; tie up the 
muslin in the form of a bag and wash under a gentle 
stream of water, manipulating well with the fingers; con- 
tinue the washing until the liquid runs clear from the 
bag, and fails to give the test for starch with iodine. 

Be careful to collect all the washings in a tall glass 
beaker or jar — they should amount to from one to one 
and a half liters. Strain through muslin and stand the 
filtrate aside in a cool place for settling. Examine the 
residue with a lens. 

Now squeeze out as much water as possible from the 
bag, untie it and collect and weigh the moist gluten ; 
spread it out in a thin cake and dry it for one hour at 
ioo°-io5° C. Cool and weigh the dry gluten. 

By this time the contents of the jar should have 



64 HOUSEHOLD CHEMISTRY. 

settled. Decant off the clear liquid, and test small 
portions of it for proteid and soluble carbohydrate. 

Pour distilled water on the residue and stir up the 
mixture, allow it to settle and decant as before. Repeat 
this operation twice, and then collect the residue on 
balanced filter-papers ; dry and weigh. 

This last weight gives the starch and fiber content, but 
in the case of ordinary wheat flours the latter is so small 
that it may be neglected. 

Note. — In the case of whole wheat flour it is best to 
pass the sample through a one hundred-mesh sieve, 
taking the screenings for the determination of starch, 
gluten, etc. 

Determination of Ash. — Incinerate about 5 grams of 
the sample in a porcelain dish, cool, and moisten the ash 
with a few drops of concentrated nitric acid. Add water, 
boil and filter, and test the filtrate (i) for potassium with 
platinic chloride, and (2) for phosphoric acid with 
ammonium molybdate. 

Rye Flour, — Examine under the microscope as under 
wheat flour. 

Take twenty-five grams of rye flour and pass it suc- 
cessively through screens of forty, sixty, eighty and one 
hundred mesh, weigh and examine the residue retained 
by each sieve and also test them for starch with iodine. 

Treat the material which has passed the one hundred 
mesh sieve for the determination of starch, gluten, etc., 
as described under wheat flours. 



TESTS ON RAW POTATOES. 65 

Ash a small portion and determine the mineral con- 
stituents as under wheat flours. 

Corn Meal (Yellow).— Examine under the micro- 
scope as before, then test a small portion in a corked 
test-tube with ether or benzine, shake vigorously and 
when the upper layer of liquid is clear decant it through 
a filter-paper and cautiously evaporate the liquid in a 
clean, dry evaporating dish. Note the character of the 
residue; what is it? 

Treat about twenty-five grams for the determination 
of starch, proteid, etc., as before. 

Make ash determinations as before. 

TESTS ON RAW POTATOES. 

1. See experiments on starch, page 26 et seq. 

2. Select a small sound potato, clean well and care- 
fully grate it over a shallow tin dish, and allow a thin 
stream of water to play upon the grater during the oper- 
ation. Not more than one quart of water should be 
used. 

3. Pour the gratings and liquid through a muslin 
strainer into a tall glass jar and allow the contents to 
settle. Examine some of the material left on the filter 
with a lens, and finally test it with iodine. 

4. When the contents of the jar have settled, draw ofi" 
some of the clear liquid and test for proteid and soluble 
carbohydrate. 

5. Test the settlings for starch. 



66 HOUSEHOI.D CHEMISTRY. 

6. To preserve these, wash several times with dilute 
salt solution, drain and dry at a low temperature. 

BREAD. 

Separate the crumb and crust. 

Crust. — Grind the darker portion to a coarse powder, 
add water, mix thoroughly and boil the mass for some 
time with more water, cool and filter, divide the filtrate 
into four parts and test as follows : 

1. Add iodine solution and note the result. 

2. Observe the taste; explain. 

3. Add to Fehling's solution and boil ; note the result. 

4. Pour a few drops into strong alcohol. 

Crumb. — Test the crumb as follows : to a portion add 
iodine solution. On another portion make test for in- 
soluble proteid (gluten). Which test is best ? 

Burn some crumb to a gray ash in a porcelain dish, 
cool, digest ash with warm nitric acid and divide into 
three parts. Test one part for chlorides, another for 
phosphates with ammonium molybdate, and the re- 
mainder for potassium with platinic chloride. 

Experiments on Toast. — Grind to powder, treat one 
teaspoonful (level) with boiling water for five minutes, 
filter hot, cool and divide liquid into four parts, and test 
as follows : 

1 . With iodine solution. 

2. With Fehling's solution. 

3. With tannic acid. 

4. Add a few drops of the cooled liquid to strong alcohol. 



BREAD. 67 

Prepared Cereals or "Breakfast Foods." — This classi- 
fication includes the various commercial preparations of 
oats, corn, barley, wheat and rice, or mixtures of the 
same. They are supposed to have undergone some 
operation of cooking and claim to contain no raw starch. 
The following general tests will serve to give some idea 
as to the condition of the material and the presence or 
absence of the various food principles : 

1. Powder the material as finely as possible in a 
mortar or coffee-mill. Pass the grindings through a 
one hundred-mesh sieve and examine the screenings and 
siftings separately under the miscroscope, finally staining 
with iodine and examining for the presence of unbroken 
starch grains. 

2. Extract a portion of both screenings and siftings 
with cold water, filter and examine the filtrates separately 
for dextrine (by precipitation with alcohol and color 
test with iodine), for glucose or reducing sugars with 
Fehling's solution, for maltose with phenyl hydrazine 
(see under glucose). 

3. Test portions of the insoluble residue separately for 
proteid, by the usual tests. 

4. Mineral Matter. — Incinerate a fresh portion of the 
screenings in a porcelain dish, cool and extract the mass 
with water, filtering and testing the filtrate for chlorides, 
sulphates and phosphates of potassium and sodium. 

Now treat the insoluble residue with a little con- 
centrated nitric acid and boil. Cool, dilute with water, 
filter if necessary and test the clear liquid for phosphates 
and for calcium. 



68 HOUSEHOLD CHEMISTRY. 

Vinegar.— Cider or malt vinegar is best for these tests. 

1. Make test for acidity with litmus paper. 

2. Take lo cc, dilute to loo cc. with distilled water, 
add a few drops of phenolphthalein and titrate with half- 
normal caustic soda solution as explained in the appendix. 

3. Make the usual ethyl acetate test for acetic acid. 

4. Distil a small quantity of vinegar diluted with a 
small quantity of water and test the distillate for acidity 
and for acetic acid. 

5. Boil a small quantity of vinegar in a beaker, re- 
place the liquid lost with boiling water, occasionally 
hold a piece of blue litmus paper in the vapor, and con- 
tinue the boiling until the liquid no longer reacts acid. 
Explain this phenomenon. 

6. Evaporate to dryness the liquid from the previous 
experiment. Note the character and odor of the residue. 
Incinerate and test the ash in the usual way for sul- 
phates, chlorides and potassium. 

7. Filter a sample of highly colored vinegar several 
times through well-ignited bone-black and observe the 
loss of color. 

8. Add basic acetate of lead to cider vinegar as long as 
a precipitate appears, filter and observe the character of 
the filtrate. 

9. Note the solvent and the neutralizing action on 
alkalies and various carbonates, such as soda, chalk, also 
egg shell, already referred to. 



DIGESTIVE FLUIDS AND THEIR ACTION : SALIVA, 
GASTRIC JUICE, PANCREATIC FLUID. 

Saliva. — Examine small quantities of saliva, prepared 
as previously described, in the following way : 

1. Under the microscope. 

2. Reaction with litmus paper. 

3. Silver nitrate and nitric acid. 

4. Barium chloride and hydrochloric acid. 

5. Nitric acid and ammonium molybdate. 

6. Ferric chloride. 

7. Make a portion distinctly acid with acetic acid and 
note the stringy precipitate of mucin. 

8. Millon's reagent. 

9. Action of Saliva on Starch. — See under dextrine. 
Also try the action on starch paste of a little saliva made 
acid with hydrochloric acid and then test with iodine. 

10. On other portions of starch solution make com- 
parative tests, first on the saliva with Fehling's solution 
and with iodine, then with starch paste and saliva 
mixed, with Fehling's solution, then with dry raw 
starch and saliva. 

Artificial Gastric Juice. — (Pepsin and 0.2 per cent, 
hydrochloric acid.) Repeat the experiments on small 
wedge-shaped pieces of hard-boiled white of Qgg with ( i ) 
dilute (0.2 per cent.) hydrochloric acid, (2) pepsin, and 
(3) pepsin and hydrochloric acid. 

Test the action of pepsin hydrochloric acid on milk. 
Try the action of pepsin solution in the presence of a 
small quantity of alkali. 



yo HOUSEHOIvD CHEMISTRY. 

Pancreatic Juice. — (Pancreatin and 0.5 per cent, 
sodium carbonate. ) Water solution of pancreas contains 
amylopsin, trypsin, steapsin and rennin. 

1. Make tests on three test-tubes containing small 
portions of clear starch-paste, using the solution of pan- 
creas and adding 0.2 per cent, hydrochloric acid to the 
first, 0.5 per cent, sodium carbonate to the second, and 
making no addition to the third. Warm each test-tube 
very gently, and carefully test with iodine solution and 
also with Fehling's solution. Make a fourth test with 
starch paste but heat the pancreatin solution to boiling 
before adding it. 

2. Fibrin. — (Proteid.) — Test small portions of fibrin 
in three test-tubes with water, 0.2 per cent, hydrochloric 
acid, and 0.5 per cent, sodium carbonate, adding to each 
some pancreas solution and warming gently. Avoid over- 
heating. Make tests for peptone and alkali albumen in 
the usual manner. 

3. Oil. — Take small portions of olive oil in three test- 
tubes, add to each a small portion of pancreas solution, 
shake and allow to stand. Add to the first a little 0.2 
per cent, hydrochloric acid, to the second a little 0.5 per 
cent, sodium carbonate, and make no addition to the 
third. Cork and shake each tube vigorously and allow 
to stand for a few minutes, then compare with tube No. 3. 

4. Milk. — Place milk diluted with 5 volumes of water 
in a test-tube, and add a few drops of pancreatic extract. 
Keep at 40° C. for half an hour. The caseinogen is first 



FKRMKNTS. 71 

curdled and then dissolved, and as this occurs the milk 
changes from a white to a yellowish color. 

Divide the resulting liquid into two portions (a) and 

(a) Add dilute acetic acid; do you get a precipitate of 
caseinogen ? Why ? 

(d) On this portion try the Biuret test for the presence 
of peptones. 

riilk'Curdling Ferments. — 

1 . Add a drop or two of brine extract of pancreas pre- 
pared for you to 5 cc. of warm milk in a test-tube, and 
keep at 40° C. Within a few minutes look for a solid 
coagulum and a separation of whey. 

2. Repeat No. i but add a grain or less of bicarbonate 
of soda to the milk. Coagulation should occur just as 
before, so that this ferment is active in an alkaline solu- 
tion. 

3. Boil the ferment first; its power is destroyed. 

FERMENTS. 

Action of Ferments and Their Prevention. Yeast. 

Temperature Experiments. — Prepare four six-inch test- 
tubes with perforated corks, bearing tubes bent in the 
form o( an inverted letter J. Fill three of the tubes with 
a mixture prepared from one-half a yeast cake, one 
tablespoonful of molasses and one cup of water. Fill the 
fourth with the same preparation filtered through absorb- 
ent cotton. 

Allow tubes Nos. i and 4 to stand, while No. 2 is sub- 



72 HOUSEHOLD CHEMISTRY. 

jected to a temperature of 32° F. (produced by a mix- 
ture of pulverized ice and salt) for fifteen minutes. No. 
3 is boiled for two or three minutes. Now place the four 
pieces of apparatus so that the delivery tube of each 
reaches to the bottom of a test-tube containing about two 
inches of clear lime-water, and allow them to stand for at 
least twelve hours in a warm place (70° F). 

At the end of this time examine each tube of lime- 
water first for a precipitate, and second with litmus 
paper. 

Finally examine the liquid in the fermentation tubes, 
noting its odor and general appearance. 

Action of Yeast on Various Foods. — Prepare two 
solutions of sugar in water as follows : 

For the first use equal quantities of granulated sugar 
and water, for the second take one-fourth of the strong 
solution and dilute with three volumes of water. Fill 
two of the fermentation tubes already prepared with two 
sugar solutions (Nos. i and 2). Dissolve one-eighth of 
a yeast cake in about 30 cc. of milk and pour the mix- 
ture into a fermentation tube (No. 3). 

Fill a fourth fermentation tube (No. 4) with a mixture 
of one-eighth of a yeast cake dissolved in thin, clear flour 
paste. Connect all four of the fermentation tubes with 
lime-water tubes as before and allow them to stand for 
twelve hours in a warm place (70° F). Examine the 
contents of each lime-water and fermentation tube. 

Acetous Fermentation. — Make a weak solution of 
alcohol in water (5 parts of alcohol to 20 parts of water) 



ANTISEPTICS. PRKSKRVATIVES. 73 

and test with litmus paper; if acid neutralize with a weak 
solution of sodium carbonate and test a small portion 
with potassium iodide and potassium hydroxide and 
heat— the odor of iodoform shows the presence of 
alcohol. 

Divide the balance of the solution into two equal parts, 
pour one into a shallow dish and place the other in a well- 
corked bottle. After the solutions have stood for a day, 
test with litmus paper, and also by adding alcohol and 
warming gently. Note the peculiar odor (ethyl acetate- 
odor of hard cider) in the first case but not in the latter; 
explain. 

Expose a small quantity of beer to the atmosphere; 
subsequently examine for acidity with test paper and for 
acetic acid with alcohol. From the results of these ex- 
periments explain why bottled weak alcoholic beverages 
keep sweet. 

ANTISEPTICS. PRESERVATIVES. 

Borax. — i. Make a weak solution in water and test 
the solution with litmus. Add a few drops of hydro- 
chloric acid, dip a strip of turmeric paper in this liquid, 
remove and dry by steam heat. This may be accomplished 
by wrapping the paper around the upper part of a 
test-tube partly filled with water and boiling gently— 
the paper turns pink on the edges. 

2. To a small quantity of powdered borax in a porce- 
lain dish add enough alcohol to moisten and 10 drops of 
glycerine, mix well with a glass rod and ignite the mass 



74 HOUSKHOLD CHEMISTRY. 

with a match or Bunsen burner. Note the yellow flame 
with a green edge, characteristic of borax. 

Repeat the same tests on boracic acid, omitting the 
addition of hydrochloric acid. 

Sodium Chloride. — Make the usual test for chlorides 
with nitric acid and silver nitrate, test for sodium by 
dipping a clean platinum wire into the salt solution and 
then holding in the flame of a Bunsen burner — a yellow 
flame indicates sodium. (To clean the platinum wire, 
hold it in the flame until all the sodium is burned away). 
Evaporate a drop of strong salt solution on a slide and 
study the crystals under the microscope (hopper-shaped 
crystals). 

Salicylic Acid. — Make a solution in water and note 
the taste, also test a portion by adding a few drops of 
ferric chloride (violet color). 

Formalin or " Formaldehyde." — i . To a little concen- 
trated sulphuric acid in a test-tube add a few drops of 
ferric chloride, cool and add a drop or two of formalin — 
gives a reddish violet color. 

2. To a drop or two of dilute formalin add a dilute so- 
lution of phenol (carbolic acid). Pour the mixture care- 
fully upon a little concentrated sulphuric acid— gives a 
color reaction. 

Acetic Acid. — Same as given on page 72. 

Cresol. — Place a few drops of molybdic acid dissolved 
in sulphuric acid on a white porcelain surface, then add a 



ANTISEPTICS. PRESERVATIVES. 75 

drop of the solution to be tested. Cresol, if pure, gives 
a reddish brown tint. 

Note. — The above are non-poisonous; the following 
poisonous : 

Mercuric Chloride — i. To a solution of mercuric 
chloride add a solution of stannous chloride — gives a 
white precipitate which turns black on standing. 

2. To a solution of mercuric chloride add a solution of 
potassium iodide — gives characteristic color reaction. 

Ferrous Sulphate — Dissolve a crystal of ferrous sul- 
phate in cold water and add a solution of potassium 
ferricyanide — blue. 

Potassium Permanganate.— i. Characteristic color is 
violet. 

2. To a little potassium permanganate solution add a 
hot solution of oxalic acid containing a little sulphuric 
acid — the color is destroyed. 

Carbolic Acid. — Note its characteristic odor, also look 
for yellow color with (i) nitric acid, (2) white precipi- 
tate with bromine water. 

Action of Alkalies and Vegetable Acids on fletals 
and their Oxides (Copper, Zinc, Iron, Lead, Tin, 
Aluminum and Arsenic). iV^/^.— Use caustic soda or 
potash for the representative alkali, acetic and tartaric 
or citric acids for the acid. Each student is expected to 
make a tabular statement of the results of the following 
tests : 



76 HOUSKHOI.D CHEMISTRY. 

Copper. — Treat bright strips of metallic copper for a 
few minutes with a few cubic centimeters of (i) tartaric 
acid, (2) acetic acid, (3) caustic potash. Allow these to 
stand in the cold and note the change if any, then gently 
heat each to boiling. Pour off the liquid and test for ma- 
terial in solution. The presence of copper will be shown 
by a blue color which will be intensified by adding a few 
drops of ammonia. Now heat the strips of copper in the 
flame until they are coated with a deposit of oxide and 
then repeat the same tests. 

Zinc. — Repeat the above tests on clean and tarnished 
zinc as far as the action of acids and alkali is concerned. 
Zinc in solution is indicated by a copious precipitate with 
potassium ferrocyanide. 

Iron. — Treat bright and tarnished iron with the above 
designated acids and alkali, pour off the solutions 
(dividing each into two parts) and test with (i) tannic 
acid, (2) potassium ferrocyanide. 

Lead. — Treat bright and tarnished lead with the same 
acids and alkali, pour off the solutions and test each with 
(i) hydrogen sulphide, (2) potassium iodide. 

Tin. — Repeat the same experiment on bright and 
tarnished tin and test the solutions with mercuric 
chloride. 

Aluminum. — Treat one or two pieces of aluminum foil 
with the above-named acids and alkali, pour off the 
solutions, note the peculiar puckering taste acquired by 
the acid solutions and the gas evolved by the alkali (try 



BAKING-POWDERS. yy 

to light it.) Make a separate test with a few fragments 
of aluminum and some dilute nitric acid; note the color 
and test paper reaction of the gas evolved. 

Arsenic.—Ars^mc is the most poisonous of the metallic 
compounds. It may be present in the enamel linings of 
cooking utensils or even low-grade tinware. The best 
test is known as Reinsch's test and is conducted as 
follows : 

A small portion of material supposed to contain arsenic 
is reduced to a fine state of division and gently boiled in 
a test-tube with concentrated hydrochloric acid and a 
strip of bright copper; a gray metallic deposit upon the 
copper may be arsenic, antimony, or mercury. In order 
to confirm the arsenic, remove the strip, dry carefully 
and introduce into a small piece of glass tubing. Hold 
this in a horizontal position over a burner and heat 
strongly— note the white deposit some distance from the 
point of heating. Examined under the magnifying glass 
this will be found to consist of minute octahedral crystals 
of arsenious oxide, white arsenic, As^Og. 

BAKING-POWDERS. 
Three General Types -Tartrate, Phosphate, Alum. 

I. Tartrates.— Mixtures of cream of tartar and bicar- 
bonate of soda with starch or lactose filler. Treat a 
small portion of the powder with water and after the 
effervescence has ceased test a portion of the liquid for 
starch with iodine solution and for lactose with Fehling's 



78 HOUSEHOI.D CHEMISTRY. 

solution, boil the remainder of the liquid, cool and filter 
through fluted paper, and test with litmus paper. 

1. Place a few drops of the clear liquid on a slide and 
allow it to evaporate spontaneously. Examine the cleft 
rectangular crystals of Rochelle salt. 

2. Add another portion of the solution to ammoniacal 
silver nitrate (prepared by adding weak ammonia to 
silver nitrate solution until the brown precipitate first 
formed has almost disappeared), and warm gently — 
notice the brilliant silver mirror due to the reducing 
action of the tartrate. Compare with dextrose. 

3. Test another portion of the solution by adding one 
drop of fresh cold solution of ferrous sulphate, one or 
two drops of peroxide of hydrogen and a large excess of 
caustic potash — a violet color due to tartrates. Evaporate 
the balance of the solution in a porcelain evaporating dish, 
char and gently ignite the residue; note the odor while 
carbonizing, what does it suggest ? Cool, add water and 
test with litmus paper; note the result. 

Note. — Tartrate powders may contain a small amount 
of bicarbonate of ammonia; to test for this, heat a small 
portion of the powder in a test-tube with caustic potash 
solution; observe the odor; or hold a strip of moistened 
red litmus paper over the mouth of the tube. 

II. Phosphate Powders. — Calcium hydrogen phos- 
phate, bicarbonate of soda and starch filler. Make a 
water solution and test for filler as in (I) above. Divide 
the remainder of the solution into three parts. 



BAKING-POWDERS. 79 

1. Make acid with nitric acid, add a few drops to am- 
monium molybdate and warm — yellow precipitate indi- 
cates phosphates. 

2. Add ammonium oxalate, and ammonium hydroxide 
until alkaline, and boil — white precipitate indicates cal- 
cium. This would give a yellowish red flame on plat- 
inum wire. 

3. As these powders frequently contain alum it is nec- 
essary to make a test. A portion of the solution placed 
on a slide and allowed to evaporate spontaneously will 
yield large truncated octahedra of alum. Probably the 
best method for the determination of alum is to add a 
portion of the solution to tincture of logwood diluted 
with two or three times its volume of water, finally add- 
ing an equal quantity of ammonium carbonate. In the 
presence of alum the liquid is colored lavender or dark 
blue. 

III. Straight Alum Powder. — Consists of bicarbonate 
of soda with potassium, sodium, or ammonium alum, and 
filler. Make water solution and test for filler as above. 
Boil the solution, filter and test the filtrate. 

1. Tincture of logwood. 

2. To a portion add potassium hydroxide, heat, note 
the odor and reaction with moist litmus paper. 

3. Evaporate the balance of the liquid to dryness in a 
porcelain dish, ignite gently, cool and make flame test on 
residue. 

To make flame test, a piece of platinum wire is moist- 
ened with hydrochloric acid and held in the Bunsen 



8o HOUSEHOLD CHEMISTRY. 

flame until it imparts no color to it. Now heat the wire 
and dip it into the material while hot, replace in the 
flame and note the color produced — sodium flame is yel- 
low; potassium, violet; lime, reddish. In the presence of 
sodium the other colors are invisible unless viewed 
through blue glass, which cuts out the yellow rays. 

Note, — The best method of determining alum in bread 
or water is the tincture of logwood method. 



Appendix. 

Scheme for the Separation and Detection of the Anions, 

CO3, P0„ SO,, and CI and the Cations Fe, 

Ca, Mg, NH,, Na and K. 

The substance occurring in solid form. In the case of a 
liquid only the acid need be added. 

Treat a small portion of the powder with H^O and enough 
HNO to make the solution acid, boiling towards the close of 
the operation; only a small residue should remain at this 
point ; if otherwise, add a little more acid and boil again; 
cool and filter, rejecting any residue. The filtrate must be 
perfectly clear before proceeding with the analysis ; if it is 
not, filter once more. Note whether there is any effervescence 
when the mixture of water and acid is poured upon the 
powder ; if so, it indicates the presence of carbonates, CO^. 
The gas evolved should be passed into clear lime-water, 
which will cloud if CO^ is present. 

The clear solution is now divided into three parts — A = V^. 

Operation with Solution A V,. 

Add an equal bulk of ammonium chloride and then 
ammonium hydroxide (NH^OH) until distinctly alkaline 
(odor of ammonia is sufficient) ; boil the mixture. If any 
precipitate forms, filter the mixture ; wash with one change 
of water. 

Precipitate. Ferric hydroxide, a brown gelatinous mass; 
dissolve this on the filter by pouring over it a small quantity 
of hot dilute hydrochloric acid ; collect the clear yellow fil- 



82 HOUSEHOLD CHEMISTRY. 

trate and add to it a few drops of ammonium thiocyanate ; 
a deep blood-red color indicates iron. 

Filtrate, clear and colorless; while still warm, add ammo- 
nium carbonate, shake well, allow the precipitate to settle 
and cautiously add a little more ammonium carbonate ; if no 
further cloud occurs, enough has been used ; now pour the 
mixture upon a filter and wash with one change of water. 

Precipitate. Calcium carbonate, a white granular mass; 
dissolve this in the least possible quantity of acetic acid on 
the filter. To the clear colorless solution add ammonium 
hydroxide until alkaline, and an equal bulk of ammonium 
oxalate ; boil the mixture. A white granular precipitate of 
calcium oxalate indicates calcium. This should give a red 
flame on heated platinum wire. 

Filtrate, clear and colorless ; divide into two equal parts 
D and E. To D add sodium phosphate and ammonium hy- 
droxide and shake well ; if a precipitate does not appear at 
once, cool the mixture and allow it to stand ten minutes. A 
white crystalline precipitate indicates magnesium. If mag- 
nesia has been found in D, pour E into a clean porcelain dish 
and evaporate off the liquid. When dry, heat until white 
fumes (ammonium salts) are no longer evolved. Cool and add 
a small amount of water, filter, and reject the residue. Add 
two drops of hydrochloric acid to the clear filtrate, dip in it 
a clean platinum wire and test in the flame. A yellow 
color indicates sodium; a violet flame, potassium (both to be 
viewed through blue glass). Potassium may be present 
even though the flame is yellow ; in this case add to the fil- 
trate a few drops of platinic chloride and shake the mixture ^ 
A yellow crj^stalline precipitate indicates potassium. 



APPENDIX. 83 

Operation with B V^. 
Make strongly alkaline with potassium or sodium hydrox- 
ide, boil and hold a piece of moistened pink litmus paper in 
the vapor arising from the boiling mass, being careful that 
none of it is spattered on the paper. The paper turning 
blue when moist and back again to pink when dry 
indicates ammonia. Where the quantity is large the odor 
is distinctive. 

Operation with C V^. 

Divide into three equal portions: 

Part I. Add to this a few drops of silver nitrate; a white 
curdy precipitate of silver chloride, soluble in ammonium 
hydroxide, indicates chlorides. 

Part II. Add two drops of hydrochloric acid and a little 
barium chloride; a w^hite crystalline precipitate of barium 
sulphate, giving a green flame on heated platinum wire, 
indicates sulphates. 

Part III. Add a few drops (not more than 10) to one inch 
of ammonium molybdate in a &' tube. Heat the mixture 
in boiling water about two minutes. A yellow crystalline 
precipitate of ammonium phosphomolybdate indicates 
phosphates. 

Normal Solutions of Acid and Alkali. 

A normal solution is one which contains the hydrogen 
equivalent of the substance in grams in one liter of solution. 
For all monobasic acids and alkalies the hydrogen equiva- 
lent corresponds with the molecular weight of the compound; 
for dibasic substances it is one-half of the molecular weight. 
In similar manner tri- and tetrabasic bodies have hydrogen 
equivalents corresponding to one-third and one-quarter of 
their molecular weights. 



84 HOUSEHOLD CHEMISTRY. 

Normal solutions may be made of one-tentli or one- 
hundredth of their full strength, either by taking the corre- 
sponding fractions of their respective equivalents or by dilu- 
ting the full normal solutions proportionately; they are 
known as deci- and centinormal solutions respectively. 

To explain the preparation of the normal solutions of acid 
and alkali, one example from each class will suffice and as 
hydrochloric acid and caustic soda have the most extensive 
application, their preparation will be given. Neither the acid 
nor alkali can be weighed or measured with accuracy, hence 
it is first necessary to make up solutions of some acid or 
alkali which can be made exact. Sodium carbonate, whose 
equivalent is 53, can be obtained of a high degree of purity 
and may be weighed exactly. It is hardly necessary to make 
up a large quantity, so that 5.3 grams of pure dry soda are 
usually weighed accurately, dissolved in the least quantity 
of water and the resulting solution diluted to exactly 100 cc. 
at or about 60° F. This constitutes the exact normal 
soda, I cc. of which contains 5.3 milligrams of soda. 

Of the hydrochloric acid, 36.5 grams are needed but as it is 
a volatile liquid and cannot be weighed with any accurac}^ 
it is usual to calculate the volume of the liquid from its 
specific gravity and weight, and to measure out the result in 
cubic centimeters, allowing a little for loss. The calcu- 
lation is simple and is made as follows: Divide the 
equivalent in grams (36.5) by the specific gravity of the 
concentrated acid (1.2); this gives 30.4+ as a quotient and is 
the number of cubic centimeters to be used if the acid were 
pure, but the strongest acid is only 40 per cent.; hence this 
quotient must be multiplied by 2.5. (30.4 X 2.5 =76 cc.) It 
is safe to take 78-80 cc, adding it to 300 or 400 cc. of distilled 
water and when cool diluting to exactly one liter. To fix 



APPENDIX. 85 

the strength exactly and make it equivalent to the soda 
solution proceed as follows : Measure 10 cc. of the soda 
very exactly with a pipette, run it into a small beaker con- 
taining about 100 cc. of distilled water, and add two or three 
drops of methyl orange solution. Now fill a burette with the 
acid solution, note the level, and run it, drop by drop with 
constant stirring, into the soda; stop when the last drop 
changes the color from yellow to pink which remains even 
after stirring for some moments. Read the burette and note 
the number of cubic centimeters, and fractions used; say the 
quantity is 9.8 cc, indicating that this quantity contains as 
much acid as should exist in 10 cc; consequently, 980 cc. of 
the liquid should be diluted to one liter. If the total amount 
of acid is less, calculate what bulk it should occupy and dilute 
accordingly. The acid keeps very well but should be pre- 
served in tightly stoppered glass bottles to prevent evapora- 
tion. 

The caustic soda is deliquescent and absorbs carbon 
dioxide, so must be weighed rapidly and approximately, 
using rather more than the 40 grams required, say 50 grams; 
this is dissolved in 300 or 400 cc of water, cooled 
and diluted to one liter. Now draw off 10 cc. of the normal 
acid in a pipette, allow it to run into a small beaker contain- 
ing about 100 cc. of distilled water, and add a few drops of 
phenol phthalein. Fill a clean, dry burette with the caustic 
soda, note its level and run it, drop by drop with constant 
stirring, into the acid solution until a faint but distinct pink 
tint remains after stirring for some moments. Read off the 
quantity used, say 9.5 cc, showing the solution to be too 
strong and requiring dilution as in the case of the acid. 
After performing this operation the acid and alkali should 
be correct and i cc. of one will exactly neutralize an equal 
quantity of the other. 



86 HOUSEHOIvD CHEMISTRY. 

To test unknown substances, first determine the body- 
present by qualitative analysis, and then weigh or measure 
some convenient quantity, dissolve or dilute with distilled 
water, add the indicator and run in the acid or alkali until 
the neutral point is reached. Observe the number of cubic 
centimeters used and multiply each by its value in milli- 
grams of the substance sought and divide the result by the 
quantity used; multiplying this quotient by loo will yield 
per cent. 

Value of I cc. of normal soda in each of the following : 

Aceticacid 0.060 

Lactic acid 0.126 

Tartaric acid 0.075 

Citric acid 0.131 

Hydrochloric acid 0.0365 

Nitric acid 0.063 

Sulphuric acid 0.049 

Potassium hydroxide 0.0561 

Ammonium hydroxide 0.035 

STAINS. 

Removal of stains depends on the nature of the fabric and 
quality of the dye. 

I. Fabrics : 

1. Silk — most easily damaged. 

2. Wool — next. 

3. Cotton— least. 

II. Dyes : 

1. Natural dyes least liable to injury. 

2. Artificial dyes (except indigo and alizarine) 

most susceptible to change. 
Caution : Do not put gasoline or ether on a wet 
fabric. 



APPENDIX. 87 

III. Solvents: i. Water. 2. Alcohol. 3. Ether. 4. Gasoline. 

IV. Absorbents: i. Talc. 2. Starch. 3. Paper. 
V. Detergents : i. Neutral soda or potash soaps. 

VI. Bleaches: i. Peroxide of hydrogen. 

2. Hypochlorites of sodium or potassium . 

3. Hyposulphite of sodium. 
VII. Neutralizing agents : 

1. Ammonia. 

2. Oxalic acid or acid oxalate of potassium. 

3. Muriatic acid, very dilute. 

4. Acetic acid. 

Steaming, used when softening old stains or 
in very delicate fabrics. 
VIII. Removal of stains and spots, caused by : 

1. Fatty bodies as grease or oil. 

Use {a) ether, {b) gasoline, {c) talc, {d) starch, 
{e) paper. 

2. Fruits : {a) Coloring matter. 

Use bleaches — salts of lemon (bin- 
oxalate of potash). 
{b) Acids. Use dilute ammonia. 

3. Mineral matter. 

{a) Rust. 

Use(i) acids (on dyedfabics), (2) oxalic, 
(3) citric, (4) tartaric. 
{b) Acids. 

Use ammonia. 

4. Fungoid growths as mildew. 

Use milk of lime and a bleach. 
{a) Javelle water. 
{b) Labarraques solution. 
{c) Peroxide of hydrogen. 



88 HOUSEHOI.D CHEMISTRY. 

{d) Sunlight. 
{e) Milk. 

5. Ink. Iron base : 

Use (i) Oxalic acid. 
(2) Salts of lemon. 

6. Sugar and gum. 

Use warm water only. 

7. Paint and varnish : 

If moist, use gasoline. 

If dry, soften with amyl acetate or pine tar 
oil and then remove with gasoline. 



of C. 



;T 2S 1904 



